Electrical Measuring Instruments questions

The opposite figure shows the internal structure of a moving-coil galvanometer. The component made of agate to reduce friction while the coil moves is ..........

1. A component (1)
2. B component (2)
3. C component (3)
4. D component (4)

The opposite figure shows the internal structure of a moving-coil galvanometer. The component made of copper is ..........

1. A component (1)
2. B component (2)
3. C component (3)
4. D component (4)

Which of the following figures represents the scale of a sensitive galvanometer that can be used to determine the direction of the electric current?

1. A A
2. B B
3. C C
4. D D

The magnetic torque acting on the galvanometer coil due to a current passing through it always equals ..........

1. A BIAN sin 0
2. B BIAN sin 45
3. C BIAN sin 90
4. D BIAN sin 30

The resultant torque acting on the galvanometer coil when its pointer settles at a certain reading equals ..........

1. A BIAN
2. B 2 BIAN
3. C 2 BIAN sin θ
4. D zero

When a current is passed through the coil of a sensitive galvanometer, its pointer takes a time t to deflect from zero and settle at a certain reading. What happens during that time to the magnetic torque $(\tau_1)$ acting on the coil and the torsion torque $(\tau_2)$ of the two spiral springs respectively?

1. A $\tau_1$: increases, $\tau_2$: constant
2. B $\tau_1$: increases, $\tau_2$: increases
3. C $\tau_1$: constant, $\tau_2$: constant
4. D $\tau_1$: constant, $\tau_2$: increases

When a direct current (I) is passed through the coil of a galvanometer, the torque acting on the coil does not change while it rotates, because of ..........

1. A the spiral springs
2. B the agate bearings
3. C the aluminium pointer
4. D the concave magnet poles together with a soft iron core

Which of the following graphs expresses the relation between the angle (θ) through which the galvanometer pointer is deflected from zero and the torque (τ) acting on the galvanometer coil due to a direct current?

1. A A
2. B B
3. C C
4. D D

When a direct current of suitable intensity passes through a moving-coil galvanometer, which quantity changes from the moment the pointer starts moving until it settles at a certain reading?

1. A The magnetic torque acting on the coil
2. B The torque due to the twisting of the two spiral springs
3. C The sensitivity of the galvanometer
4. D The angle between the coil and the direction of the magnetic flux

When an alternating current of low frequency (1 Hz) passes through a galvanometer, its pointer ..........

1. A does not deflect from the zero of its scale
2. B deflects and settles at a certain value
3. C oscillates about the zero of its scale
4. D deflects to the end of its scale

When a high direct current passes through the galvanometer coil ..........

1. A the galvanometer pointer is not deflected
2. B no torque acts on the galvanometer coil
3. C a high heat is produced that may damage the coil
4. D the sensitivity of the galvanometer increases

If a galvanometer pointer is deflected through 50° when a current of 500 μA passes, the sensitivity of the galvanometer equals .......... deg/μA

1. A 550
2. B 450
3. C 0.1
4. D 10

A galvanometer has a sensitivity of 2 deg/μA. If the value of one division is 5 μA and the maximum deflection angle of the pointer from zero is 50°, the number of divisions on the galvanometer scale equals ..........

1. A 5 divisions
2. B 10 divisions
3. C 20 divisions
4. D 25 divisions

The scale of a sensitive galvanometer has twenty divisions, and its pointer deflects to the middle of the scale when a current of 0.1 milliampere passes through its coil. The value of one division on the scale equals ..........

1. A 20 microamperes
2. B 10 microamperes
3. C 5 microamperes
4. D 2 microamperes

The pointer of a moving-coil galvanometer deflects to half the scale when a current of 200 μA passes. If the value of one division is 0.08 mA, the number of divisions on the galvanometer scale equals .......... divisions.

1. A 10
2. B 9
3. C 7
4. D 5

The following figures show the deflection of the pointers of four sensitive galvanometers when the same current passes through each. Which of them represents the galvanometer with the greatest sensitivity?

1. A A
2. B B
3. C C
4. D D

The following figures show the deflection of the pointers of four sensitive galvanometers when a current of 250 μA passes through each. Which of these instruments has a sensitivity of 0.16 deg/μA?

1. A A
2. B B
3. C C
4. D D

Two copper wires of the same length are used to make the coils of two galvanometers P and Q. Each wire is wound around a square aluminium frame of side X and 2X respectively. If the two galvanometers are identical in the magnetic flux density acting on the coil and the elasticity constant of the two spiral springs, the ratio of the sensitivity of galvanometer (P) to that of galvanometer (Q) equals ..........

1. A $\dfrac{1}{2}$
2. B $\dfrac{1}{4}$
3. C $\dfrac{2}{1}$
4. D $\dfrac{1}{1}$

A galvanometer coil of cross-sectional area 6 cm² and 600 turns is suspended in a magnetic field of flux density 0.1 T. The current needed to produce a torque of $4.32 \times 10^{-3}$ N.m equals ..........

1. A 0.01 A
2. B 0.02 A
3. C 0.12 A
4. D 0.21 A

A sensitive galvanometer has a coil of 1200 turns, each of face area 3 cm², rotating in a uniform magnetic field of flux density 0.01 T. When a current of 1 mA is passed through the coil, the pointer deflects from zero through 30°. The torsion torque in the two spiral springs when the pointer settles equals ..........

1. A $2.55 \times 10^{-6}$ N.m
2. B $3.6 \times 10^{-6}$ N.m
3. C $4.22 \times 10^{-6}$ N.m
4. D $6.4 \times 10^{-6}$ N.m

A sensitive galvanometer with terminals a and b, resistance R and its zero at the middle of the scale deflects to position ℓ when connected in the circuit shown in the following figure.
When the galvanometer swaps places in the circuit with resistance $R_1$, so that its terminal a is connected to point c and its terminal b to point d, the galvanometer pointer deflects to position ..........

1. A x
2. B y
3. C z
4. D k

The smaller the shunt connected to the galvanometer, the sensitivity of the ammeter ..........

1. A increases
2. B decreases
3. C stays the same
4. D increases then decreases

The ratio of the resistance of the shunt to the resistance of the whole ammeter is .......... one.

1. A greater than
2. B equal to
3. C less than
4. D cannot be determined

In an ammeter, if the shunt connected to the galvanometer is decreased and the same current is passed through the ammeter, the quantity that increases is ..........

1. A the torsion torque acting on the two spiral springs of the galvanometer
2. B the magnetic force acting on the sides of the galvanometer coil
3. C the sensitivity of the ammeter
4. D the accuracy of the ammeter in measuring the current

An ammeter connected in a circuit deflects to the end of its scale. What happens to the galvanometer if the resistance of the shunt is increased and the same current passes through the ammeter?

1. A Its pointer deflects in the opposite direction
2. B Its sensitivity decreases greatly
3. C A current less than its full-scale reading passes through its coil
4. D A current greater than its full-scale reading passes through its coil

In an ammeter, the range for measuring current is greatest when the galvanometer is connected to a shunt whose resistance is ..........

1. A one third of the galvanometer resistance
2. B twice the galvanometer resistance
3. C half the galvanometer resistance
4. D one fifth of the galvanometer resistance

The pointer of a moving-coil galvanometer deflects to the end of its scale when a current (I) passes through it. A 12 Ω resistance was connected in parallel with its coil, and its pointer deflected to one fifth of the scale when the same current (I) was passed. The resistance of the galvanometer coil $(R_g)$ is ..........

1. A 24 Ω
2. B 36 Ω
3. C 48 Ω
4. D 60 Ω

If the ratio of the resistance of an ammeter to the resistance of the galvanometer inside it is $\frac{1}{10}$, the ratio of the shunt resistance to the galvanometer resistance is ..........

1. A $\dfrac{1}{10}$
2. B $\dfrac{10}{1}$
3. C $\dfrac{1}{99}$
4. D $\dfrac{1}{9}$

For a galvanometer of coil resistance R, the shunt resistance that reduces the sensitivity of the galvanometer to one quarter is ..........

1. A R
2. B $\dfrac{R}{2}$
3. C $\dfrac{R}{3}$
4. D $\dfrac{R}{4}$

A shunt of resistance 0.1 Ω reduces the sensitivity of an ammeter to one tenth. The resistance of the shunt that reduces the sensitivity of this ammeter to one quarter equals ..........

1. A 0.2 Ω
2. B 0.3 Ω
3. C 0.6 Ω
4. D 0.9 Ω

In the opposite figure, a shunt is connected to a galvanometer through a switch K. When the switch is closed, the sensitivity of the instrument decreases to ..........

1. A one half
2. B one fifth
3. C one sixth
4. D one quarter

A galvanometer of resistance (R) is connected to a shunt of $\left(\frac{R}{3}\right)$ through a switch (S) to form an ammeter. When a current (I) passes through the galvanometer, its pointer deflects as in the opposite figure. If switch (S) is closed and the same current passes through the ammeter, the galvanometer pointer deflects to position ..........

1. A x
2. B y
3. C z
4. D k

An ammeter consists of a galvanometer and a shunt whose resistance equals that of the galvanometer. When a current I passes through the ammeter, the galvanometer pointer deflects through an angle θ as in the opposite figure. If the shunt resistance is decreased to one third of the galvanometer resistance with the same current (I) in the ammeter, the deflection angle of the pointer from zero becomes ..........

1. A θ
2. B $\dfrac{\theta}{2}$
3. C $\dfrac{\theta}{3}$
4. D $\dfrac{\theta}{4}$

An ammeter has a galvanometer of resistance $R_g$. When it is connected in a closed circuit, 2% of the circuit current passes through the galvanometer. The resistance of the shunt equals ..........

1. A $\dfrac{R_g}{50}$
2. B $\dfrac{R_g}{49}$
3. C $49 R_g$
4. D $50 R_g$

A galvanometer of resistance 54 Ω is connected to a shunt $R_s$ so that 0.1 of the total current passes through the galvanometer. The resistance $R_s$ equals ..........

1. A 4.5 Ω
2. B 6 Ω
3. C 8.25 Ω
4. D 10 Ω

A galvanometer of resistance 36 Ω has a 4 Ω shunt connected to its coil, and the resulting instrument is connected in a closed circuit. The percentage of the current passing through the galvanometer to the total current equals ..........

1. A 8 %
2. B 9 %
3. C 10 %
4. D 91 %

A galvanometer with a coil resistance of 0.1 Ω reads a current $I_g$ at the end of its scale. The shunt resistance needed to increase its range to 10 times equals ..........

1. A 0.03 Ω
2. B 0.02 Ω
3. C 0.01 Ω
4. D 0.003 Ω

A sensitive galvanometer is connected to a multi-way switch that can connect it to one of the numbered positions (1, 2, 3, 4) to convert it into an ammeter. The ammeter has the greatest range when the switch is at position ..........

1. A 1
2. B 2
3. C 3
4. D 4

A galvanometer of resistance 54 Ω deflects to the end of its scale when a current of 0.01 A passes through it. It is to be modified to measure a current of 0.1 A, so ..........

1. A the shunt is 6 Ω, connected in series with the galvanometer
2. B the shunt is 3 Ω, connected in series with the galvanometer
3. C the shunt is 6 Ω, connected in parallel with the galvanometer
4. D the shunt is 3 Ω, connected in parallel with the galvanometer

In the opposite figure, a moving-coil galvanometer deflects through an angle θ to the end of its scale when a current $(I_g)$ passes through its coil. When a shunt is connected to the galvanometer to convert it into an ammeter and the same current $(I_g)$ is passed through the ammeter, the deflection angle of the pointer decreases by 75%. The sensitivity of the instrument ..........

1. A increased by 75 %
2. B decreased by 75 %
3. C increased by 25 %
4. D decreased by 25 %

A galvanometer is connected in a circuit whose components are connected in series. The two graph lines M and N in the opposite figure represent the relation between the deflection angle of the galvanometer pointer (θ) and the current (I) in the circuit before and after converting it into an ammeter. The sensitivity of the ammeter equals ..........

1. A half the sensitivity of the galvanometer
2. B one third of the sensitivity of the galvanometer
3. C one quarter of the sensitivity of the galvanometer
4. D the sensitivity of the galvanometer

A galvanometer was connected to a shunt $R_1$, and the maximum current the instrument could measure was (I), as in figure (1). When the same galvanometer was connected to a shunt $R_2$, the maximum current the instrument could measure was (2 I), as in figure (2). In which figure is the potential difference across the instrument greater?

1. A In figure (1)
2. B In figure (2)
3. C Equal in both figures
4. D Cannot be determined

The opposite figure shows two identical galvanometers, each connected to a shunt to convert it into an ammeter. The ratio of the maximum currents the two ammeters measure $\left(\frac{I_x}{I_y}\right)$ is ..........

1. A $\dfrac{4}{7}$
2. B $\dfrac{2}{1}$
3. C $\dfrac{3}{1}$
4. D $\dfrac{7}{4}$

A moving-coil galvanometer has a full-scale reading of 500 μA, and its pointer deflects to it when the potential difference across it is 0.04 V. The resistance of the shunt that converts it into an ammeter measuring currents up to 500 mA equals ..........

1. A 0.07 Ω
2. B 0.035 Ω
3. C 0.4 Ω
4. D 0.08 Ω

An ammeter deflects to the end of its scale when a current of 200 mA passes through it, and when the ammeter reads 50 mA the potential difference across it is 0.04 V. The shunt that makes it suitable for measuring currents up to 2 A equals ..........

1. A 0.089 Ω
2. B 0.037 Ω
3. C 0.52 Ω
4. D 0.41 Ω

A sensitive galvanometer with a coil resistance of 50 Ω is converted into an ammeter. The opposite graph represents the relation between the current through the shunt $(I_s)$ when the galvanometer pointer deflects to the end of its scale and the reciprocal of the shunt resistance $\left(\frac{1}{R_s}\right)$. The full-scale reading of the galvanometer $(I_g)$ is ..........

1. A $2 \times 10^{-3}$ A
2. B $3 \times 10^{-2}$ A
3. C $6 \times 10^{-3}$ A
4. D $9 \times 10^{-2}$ A

An ammeter consists of a galvanometer of resistance $R_g$ and a variable resistance $(R_s)$ acting as a shunt. The opposite graph represents the relation between the current (I) measured by the ammeter and the reciprocal of the shunt resistance $\left(\frac{1}{R_s}\right)$. The resistance of the galvanometer is calculated from the relation ..........

1. A $R_g = \dfrac{L}{M}$
2. B $R_g = \dfrac{L}{KM}$
3. C $R_g = \dfrac{M}{L}$
4. D $R_g = \dfrac{L + K}{M}$

A sensitive galvanometer with a coil resistance of 6 Ω is connected to a shunt $R_s$ to convert it into an ammeter, and the ammeter is connected in a circuit. The opposite graph represents the relation between the ammeter reading (I) and the current $(I_g)$ through the galvanometer coil. The shunt $R_s$ equals ..........

1. A 0.1 Ω
2. B 0.03 Ω
3. C 0.5 Ω
4. D 0.8 Ω

A shunt of resistance $R_s$ is connected to each of three galvanometers of different resistances, separately, to form three ammeters x, y and z, as in the following figures.
Which of the following graphs represents the relation between the current measured by the ammeter (I) and the current through the galvanometer $(I_g)$?

1. A A
2. B B
3. C C
4. D D

A moving-coil galvanometer with a coil resistance of 100 Ω has each division of its scale indicating a current of 25 mA. If its coil is connected to a shunt of resistance 0.05 Ω, the current indicated by one division becomes ..........

1. A 30.06 A
2. B 40.01 A
3. C 25.02 A
4. D 50.025 A

A moving-coil galvanometer has a maximum deflection angle from zero of 80°. If a current of 30 mA passes through it, its deflection angle from zero is 60°. Then:
the sensitivity of the galvanometer equals ..........

1. A 5 deg/mA
2. B 3 deg/mA
3. C 2 deg/mA
4. D 1 deg/mA

A moving-coil galvanometer has a maximum deflection angle from zero of 80°. If a current of 30 mA passes through it, its deflection angle from zero is 60°. Then:
the maximum current the galvanometer coil can carry equals ..........

1. A 0.02 A
2. B 0.04 A
3. C 0.06 A
4. D 0.08 A

A moving-coil galvanometer has a maximum deflection angle from zero of 80°. If a current of 30 mA passes through it, its deflection angle from zero is 60°. Then:
the maximum current the instrument can measure if its coil is connected to a shunt of 0.01 of its coil resistance equals ..........

1. A 1.51 A
2. B 2.12 A
3. C 3.75 A
4. D 4.04 A

A galvanometer with a coil resistance of 20 Ω has a shunt connected in parallel with it, consisting of a wire 20 cm long with a resistance of 5 Ω, and the maximum current the instrument measures is 1 A. If another wire of the same material and the same cross-sectional area but half the length of the first wire is used as a shunt with the same galvanometer, the maximum current the instrument measures becomes ..........

1. A 1.2 A
2. B 1.4 A
3. C 1.6 A
4. D 1.8 A

A sensitive galvanometer measures a maximum current of $8 \times 10^{-3}$ A when connected to a 1 Ω shunt, and a maximum current of $71 \times 10^{-3}$ A when connected to a 0.1 Ω shunt. Then:
(1) the resistance of the galvanometer coil equals ..........

1. A 7 Ω
2. B 9 Ω
3. C 11 Ω
4. D 15 Ω

A sensitive galvanometer measures a maximum current of $8 \times 10^{-3}$ A when connected to a 1 Ω shunt, and a maximum current of $71 \times 10^{-3}$ A when connected to a 0.1 Ω shunt. Then:
(2) the maximum current the galvanometer coil can carry equals ..........

1. A $1 \times 10^{-3}$ A
2. B $2 \times 10^{-3}$ A
3. C $3 \times 10^{-3}$ A
4. D $4 \times 10^{-3}$ A

The opposite circuit consists of a battery $V_B$ of internal resistance 1 Ω connected to a fixed resistance of 15 Ω and a galvanometer of coil resistance 20 Ω. The ratio between the currents in the circuit before and after connecting the galvanometer coil to a 5 Ω shunt equals ..........

1. A $\dfrac{5}{9}$
2. B $\dfrac{9}{5}$
3. C $\dfrac{4}{3}$
4. D $\dfrac{3}{4}$

A galvanometer with a coil resistance of 10 Ω and a maximum measurable current of 40 mA is connected to a shunt $(R_s)$, then connected in a circuit containing an 8 Ω resistance and a cell of emf 1.5 V with negligible internal resistance. When the circuit is closed, the galvanometer pointer deflects to $\frac{3}{4}$ of its scale. The shunt equals ..........

1. A 7.6 Ω
2. B 5 Ω
3. C 2.5 Ω
4. D 0.3 Ω

In the opposite figure, a galvanometer can be connected to one of two shunts or to both. When only switch $K_1$ is closed, the sensitivity of the instrument drops to one quarter and it becomes suitable for measuring a current of 0.5 A. Then:
(1) the maximum current that can be measured when only switch $K_2$ is closed equals ..........

1. A 0.45 A
2. B 0.31 A
3. C 0.25 A
4. D 0.17 A

In the opposite figure, a galvanometer can be connected to one of two shunts or to both. When only switch $K_1$ is closed, the sensitivity of the instrument drops to one quarter and it becomes suitable for measuring a current of 0.5 A. Then:
(2) the maximum current that can be measured when both switches $K_1$ and $K_2$ are closed equals ..........

1. A 0.38 A
2. B 0.43 A
3. C 0.52 A
4. D 0.69 A

A galvanometer is connected to a two-way switch (K) as in the opposite figure. When the switch is at position (1), 90% of the total current passes through the shunt $(R_s)_1$, and when the switch is at position (2), 99% of the total current passes through the shunt $(R_s)_2$. The ratio between the resistances of the two shunts $\frac{(R_s)_1}{(R_s)_2}$ equals ..........

1. A 10
2. B 11
3. C 9
4. D 99

A galvanometer with a coil resistance of 250 Ω and a maximum measurable current of 0.1 A has several resistances connected to it to form an ammeter, as in the opposite figure. When the slider is at position (x), the maximum reading of the instrument is 10 A. The maximum reading of the instrument after moving the slider to position (y) is ..........

1. A 20 A
2. B 30 A
3. C 40 A
4. D 50 A

A circuit consists of a battery of negligible internal resistance, a fixed resistance of 350 Ω and a galvanometer connected in parallel with a 20 Ω shunt. If the shunt is replaced by another of 30 Ω, the fixed resistance must be changed to 450 Ω so that the deflection of the galvanometer pointer stays the same. The resistance of the galvanometer equals ..........

1. A 20 Ω
2. B 40 Ω
3. C 60 Ω
4. D 80 Ω

Three voltmeters (A, B, C) have the same range and resistances of 1000 Ω, 4000 Ω and 8000 Ω respectively. The most accurate voltmeter when used to measure the potential difference between the same two points in a circuit is ..........

1. A voltmeter A
2. B voltmeter B
3. C voltmeter C
4. D they all have the same accuracy

In the opposite circuit, the potential difference across the 300 Ω resistance is $(V_1)$. When a voltmeter of resistance 3000 Ω is connected across the 300 Ω resistance, its reading is $(V_2)$, and when a voltmeter of resistance 6000 Ω is connected across the 300 Ω resistance, its reading is $(V_3)$. Which of the following relations is correct for $(V_1)$, $(V_2)$ and $(V_3)$?

1. A $V_1 = V_2 = V_3$
2. B $V_1 > V_2 > V_3$
3. C $V_1 > V_3 > V_2$
4. D $V_1 < V_2 < V_3$

A galvanometer deflects to the end of its scale when a current of 50 μA passes through it. It is converted into a voltmeter with a full-scale reading of 10 V. Then:
(1) the total resistance of the voltmeter equals ..........

1. A $100 \times 10^3$ Ω
2. B $200 \times 10^3$ Ω
3. C $300 \times 10^3$ Ω
4. D $400 \times 10^3$ Ω

A galvanometer deflects to the end of its scale when a current of 50 μA passes through it. It is converted into a voltmeter with a full-scale reading of 10 V. Then:
(2) the multiplier, if the resistance of the galvanometer coil is 1 kΩ, equals ..........

1. A $111 \times 10^3$ Ω
2. B $150 \times 10^3$ Ω
3. C $199 \times 10^3$ Ω
4. D $245 \times 10^3$ Ω

Four identical galvanometers, each of resistance $R_g$, are each connected to one or more resistances as in the following figures. Which of the following voltmeters can withstand the greatest potential difference?

1. A A
2. B B
3. C C
4. D D

A sensitive galvanometer can measure a maximum current $I_g$. Several multipliers are connected to the galvanometer, each separately, to convert it into a voltmeter. The opposite graph represents the relation between the maximum potential difference measured by the voltmeter (V) and the total resistance of the voltmeter (R). The value of $I_g$ is ..........

1. A 0.1 A
2. B 0.2 A
3. C 0.25 A
4. D 0.5 A

The opposite graph represents the relation between the total potential difference (V) across a voltmeter and the multiplier $(R_m)$ of the voltmeter. The value (x) divided by the slope of the line represents ..........

1. A $R_g$
2. B $V_m$
3. C $\dfrac{1}{I_m}$
4. D $V_g$

The opposite graph represents the change of the difference between the maximum potential difference measured by the galvanometer after and before connecting a multiplier $(V - V_g)$ with the multiplier $(R_m)$:
(1) the maximum current the galvanometer can carry before connecting the multiplier equals ..........

1. A 0.01 A
2. B 0.02 A
3. C 0.03 A
4. D 0.04 A

The opposite graph represents the change of the difference between the maximum potential difference measured by the galvanometer after and before connecting a multiplier $(V - V_g)$ with the multiplier $(R_m)$:
(2) if the maximum potential difference the galvanometer coil can withstand before connecting the multiplier is 1 V, the resistance of the galvanometer coil equals ..........

1. A 30 Ω
2. B 50 Ω
3. C 80 Ω
4. D 100 Ω

A sensitive galvanometer with a coil resistance of 50 Ω and a maximum coil current of 0.12 A is connected to a multiplier $(R_m)$ to convert it into a voltmeter. The opposite graph represents the relation between the voltmeter reading (V) and the current through its coil $(I_g)$. Then:
(1) the multiplier $(R_m)$ equals ..........

1. A 125 Ω
2. B 240 Ω
3. C 460 Ω
4. D 950 Ω

A sensitive galvanometer with a coil resistance of 50 Ω and a maximum coil current of 0.12 A is connected to a multiplier $(R_m)$ to convert it into a voltmeter. The opposite graph represents the relation between the voltmeter reading (V) and the current through its coil $(I_g)$. Then:
(2) the maximum potential difference that can be measured by the voltmeter equals ..........

1. A 90 V
2. B 120 V
3. C 210 V
4. D 180 V

A sensitive galvanometer can measure a maximum potential difference $(V_g)$. It is connected to two multipliers, 1 kΩ and R, each separately, to convert it into two voltmeters (1) and (2) respectively. The opposite graph represents the relation between the potential difference across each voltmeter (V) and the potential difference across the galvanometer $(V_g)$. The multiplier R equals ..........

1. A 200 Ω
2. B 400 Ω
3. C 600 Ω
4. D 800 Ω

If the multiplier resistance in a voltmeter is ten times the galvanometer resistance, the maximum potential difference measured by the voltmeter equals .......... (where $(V_g)$ is the maximum potential difference the galvanometer can withstand)

1. A $10\ V_g$
2. B $9\ V_g$
3. C $0.1\ V_g$
4. D $11\ V_g$

A voltmeter consists of a galvanometer of resistance R and a multiplier of resistance 50 R. Which of the following ratios has a value of 0.02?

1. A The ratio of the current in the galvanometer to the current in the voltmeter
2. B The ratio of the current in the galvanometer to the current in the multiplier
3. C The ratio of the potential difference across the multiplier to the potential difference across the voltmeter
4. D The ratio of the potential difference across the galvanometer to the potential difference across the multiplier

The opposite figure shows the scale of a galvanometer after calibrating it into a voltmeter scale. What does the ratio of the voltmeter scale reading to the galvanometer scale reading $\left(\frac{V}{I_g}\right)$ represent?

1. A $R_m + R_g$
2. B $R_m - R_g$
3. C $R_m R_g$
4. D $\dfrac{R_m}{R_g}$

A galvanometer of resistance 100 Ω and maximum current 0.01 A is to be converted into a voltmeter. Then:
(1) the multiplier that makes it measure potential differences up to 5 V is ..........

1. A 5 Ω
2. B 100 Ω
3. C 400 Ω
4. D 500 Ω

A galvanometer of resistance 100 Ω and maximum current 0.01 A is to be converted into a voltmeter. Then:
(2) the maximum potential difference it measures when connected to a 900 Ω multiplier is ..........

1. A 0.9 V
2. B 9 V
3. C 10 V
4. D 90 V

A galvanometer deflects to the end of its scale when a current of 0.02 A passes through it, and the potential difference across it is then 5 V. Then:
(1) the multiplier that makes it suitable for measuring a potential difference of 150 V equals ..........

1. A 2916 Ω
2. B 4374 Ω
3. C 5841 Ω
4. D 7250 Ω

A galvanometer deflects to the end of its scale when a current of 0.02 A passes through it, and the potential difference across it is then 5 V. Then:
(2) the resistance of the galvanometer coil equals ..........

1. A 110 Ω
2. B 250 Ω
3. C 315 Ω
4. D 520 Ω

In a voltmeter, the ratio of the current in the galvanometer coil to the current in the multiplier connected to it is always ..........

1. A greater than one
2. B equal to one
3. C less than one
4. D cannot be determined

The greater the multiplier resistance in a voltmeter, the ..........

1. A smaller the total resistance of the instrument
2. B greater the sensitivity of the instrument
3. C smaller the range of the instrument for measuring potential difference
4. D greater the accuracy of the instrument in measuring potential difference

A voltmeter of resistance 2000 Ω can measure a maximum potential difference of 2 V. When a multiplier $R_m$ is connected to it, its range increases by 8 V. The value of $R_m$ is ..........

1. A 2000 Ω
2. B 4000 Ω
3. C 6000 Ω
4. D 8000 Ω

A voltmeter of resistance 500 Ω has each of its divisions indicating 0.1 V. The multiplier that must be connected to the voltmeter to make each division indicate 1 V is ..........

1. A 5000 Ω
2. B 2400 Ω
3. C 4500 Ω
4. D 2700 Ω

A galvanometer with a coil resistance of 5 Ω measures a maximum current of 20 mA. Then:
(1) the maximum current the galvanometer can measure if connected to a shunt of 0.1 Ω equals ..........

1. A 0.96 A
2. B 1.02 A
3. C 3.16 A
4. D 4.05 A

A galvanometer with a coil resistance of 5 Ω measures a maximum current of 20 mA. Then:
(2) the multiplier connected to the galvanometer to make it work as a voltmeter measuring a maximum potential difference of 5 V equals ..........

1. A 100 Ω
2. B 175 Ω
3. C 245 Ω
4. D 332 Ω

A moving-coil galvanometer has a coil resistance of 18 Ω. Then:
(1) the shunt resistance that allows $\frac{1}{3}$ of the total current to pass through the galvanometer coil equals ..........

1. A 3 Ω
2. B 6 Ω
3. C 9 Ω
4. D 12 Ω

A moving-coil galvanometer has a coil resistance of 18 Ω. Then:
(2) the multiplier resistance that makes the galvanometer suitable for measuring a potential difference ten times the potential difference across its coil equals ..........

1. A 162 Ω
2. B 81 Ω
3. C 324 Ω
4. D 202.5 Ω

A moving-coil galvanometer becomes suitable for measuring a maximum current of 0.11 A when connected to a 0.5 Ω shunt, and for measuring a maximum potential difference of 2.5 V when connected to a 245 Ω multiplier. Then:
(1) the maximum current the galvanometer coil can carry $(I_g)$ equals ..........

1. A 0.5 A
2. B 0.25 A
3. C 0.01 A
4. D 0.005 A

A moving-coil galvanometer becomes suitable for measuring a maximum current of 0.11 A when connected to a 0.5 Ω shunt, and for measuring a maximum potential difference of 2.5 V when connected to a 245 Ω multiplier. Then:
(2) the resistance of the galvanometer equals ..........

1. A 5 Ω
2. B 3 Ω
3. C 2.5 Ω
4. D 1.5 Ω

In the opposite figure, a galvanometer of resistance (R) is connected to two multipliers, 7 R and 11 R. When only switch $(K_1)$ is closed, the maximum reading of the instrument is 24 V. The maximum reading of the instrument when only switch $(K_2)$ is closed decreases by ..........

1. A 6 V
2. B 8 V
3. C 12 V
4. D 16 V

In the opposite figure, part of a circuit contains a galvanometer of resistance $R_g$ and maximum current $I_g$. When switch $K_1$ is open, it becomes a voltmeter measuring a maximum potential difference of 11 V, and when both switches $K_1$ and $K_2$ are closed, the galvanometer becomes an ammeter measuring a maximum current of 0.11 A. The values of $I_g$ and $R_g$ are ..........

1. A $I_g$: 0.1 A, $R_g$: 10 Ω
2. B $I_g$: 0.1 A, $R_g$: 100 Ω
3. C $I_g$: 0.01 A, $R_g$: 10 Ω
4. D $I_g$: 0.01 A, $R_g$: 100 Ω

Two voltmeters X and Y each contain the same galvanometer and a different multiplier. Which statement correctly describes the movement of the pointer of each voltmeter when each is connected separately between points A and B in the circuit shown in the figure?

1. A The pointer of instrument X deflects through a greater angle
2. B The pointer of instrument Y deflects through a greater angle
3. C The pointers of both instruments deflect through the same angle
4. D The pointers of the two voltmeters do not deflect

A circuit contains a 10 Ω resistance connected in parallel with a voltmeter of resistance 50 Ω. When a total current of 0.6 A passes in the circuit, the voltmeter pointer deflects to the end of its scale. Then:
(1) the voltmeter reading then equals ..........

1. A 2 V
2. B 3 V
3. C 5 V
4. D 9 V

A circuit contains a 10 Ω resistance connected in parallel with a voltmeter of resistance 50 Ω. When a total current of 0.6 A passes in the circuit, the voltmeter pointer deflects to the end of its scale. Then:
(2) the maximum potential difference the voltmeter can measure if its coil is connected in series with a 4950 Ω resistance equals ..........

1. A 100 V
2. B 250 V
3. C 370 V
4. D 500 V

A circuit has a fixed resistance of 6 Ω with a voltmeter of resistance 30 Ω connected in parallel with it. When a current of 0.2 A passes in the circuit, the voltmeter pointer deflects to the end of the scale. If a resistance (multiplier) of 144 Ω is connected in series with the voltmeter and the same current passes in the circuit, then:
(1) the voltmeter reading in this case equals ..........

1. A 3.48 V
2. B 2.34 V
3. C 1.16 V
4. D 0.98 V

A circuit has a fixed resistance of 6 Ω with a voltmeter of resistance 30 Ω connected in parallel with it. When a current of 0.2 A passes in the circuit, the voltmeter pointer deflects to the end of the scale. If a resistance (multiplier) of 144 Ω is connected in series with the voltmeter and the same current passes in the circuit, then:
(2) the maximum potential difference the instrument can measure after connecting the multiplier equals ..........

1. A 7.2 V
2. B 9.6 V
3. C 11.2 V
4. D 5.8 V

An electric measuring instrument xy consists of a galvanometer, a multiplier $(R_m)$, a shunt $(R_s)$ and two switches $K_1$ and $K_2$, as in the opposite figure. When both switches are open, the sensitivity of the instrument for measuring potential difference decreases to one quarter, and when both switches are closed, the sensitivity of the instrument for measuring current decreases to one quarter. The ratio $\left(\frac{R_m}{R_s}\right)$ equals ..........

1. A 3
2. B 4
3. C 9
4. D 16

A sensitive galvanometer with a coil resistance of 4 Ω and a maximum current of 1 mA has its coil connected in parallel with a 1 Ω resistance to form one instrument. This instrument is then connected in series with a 999.2 Ω resistance to form a voltmeter. The maximum potential difference this voltmeter can measure equals ..........

1. A 2 V
2. B 5 V
3. C 7 V
4. D 9 V

A milliammeter deflects to the end of its scale when a current of 10 mA passes through it. If the instrument contains a 0.2 Ω resistance connected in parallel with a galvanometer of resistance 33 Ω, the resistance that must be connected in series to convert the milliammeter into a voltmeter measuring potential differences up to 10 V equals ..........

1. A 880.2 Ω
2. B 950.3 Ω
3. C 999.8 Ω
4. D 1250.4 Ω

A circuit contains a cell of emf 10 V and negligible internal resistance, connected to two resistances of 16 Ω and 40 Ω in series. When a voltmeter is connected in parallel with the 40 Ω resistance, it reads 6 V:
(1) the resistance of the voltmeter equals ..........

1. A 25 Ω
2. B 53 Ω
3. C 60 Ω
4. D 67 Ω

A circuit contains a cell of emf 10 V and negligible internal resistance, connected to two resistances of 16 Ω and 40 Ω in series. When a voltmeter is connected in parallel with the 40 Ω resistance, it reads 6 V:
(2) if the maximum reading of the voltmeter is 7.5 V, the shunt resistance that converts it into an ammeter measuring a maximum current of 5 A equals ..........

1. A 0.6 Ω
2. B 1.54 Ω
3. C 2.17 Ω
4. D 3.72 Ω

A galvanometer of resistance $R_g$ is connected to two multipliers, 950 Ω and 3950 Ω, each separately, to convert it into two voltmeters (1) and (2). If the ratio between the maximum potential differences the two voltmeters can measure $\left(\frac{V_1}{V_2}\right)$ equals $\frac{1}{4}$, the resistance of the galvanometer $(R_g)$ equals ..........

1. A 20 Ω
2. B 36 Ω
3. C 50 Ω
4. D 100 Ω

A galvanometer can measure a maximum potential difference $(V_g)$. When connected to two multipliers $R_1$ and $R_2$, each separately, the maximum potential difference each instrument can measure is $nV_g$ and $mV_g$ respectively. The ratio $\left(\frac{R_1}{R_2}\right)$ equals ..........

1. A $\dfrac{n-1}{m-1}$
2. B $\dfrac{n+1}{m+1}$
3. C $\dfrac{m-1}{n-1}$
4. D $\dfrac{m+1}{n+1}$

In the opposite figure, to convert the galvanometer into a voltmeter measuring the greatest possible potential difference, the switches that must be closed are ..........

1. A $K_1$, $K_4$
2. B $K_1$, $K_3$
3. C $K_3$, $K_4$
4. D $K_2$, $K_4$

When the ohmmeter circuit is closed and its pointer reaches the end of the current scale, the measured resistance is ..........

1. A large
2. B small
3. C zero
4. D infinite

The terminals of an ohmmeter are connected to the ends of a resistance R, and its pointer deflects to the middle of the current scale. The resistance R ..........

1. A is infinite
2. B equals the resistance of the ohmmeter
3. C equals zero
4. D is greater than the resistance of the ohmmeter

The opposite figure represents equal divisions on the resistance scale of an ohmmeter whose pointer was adjusted to the zero of the scale:
(1) which of the marks shown on the scale indicates the value of the ohmmeter's resistance?

1. A A
2. B B
3. C C
4. D D

The opposite figure represents equal divisions on the resistance scale of an ohmmeter whose pointer was adjusted to the zero of the scale:
(2) when the pointer settles at mark C, this means that the value C ..........

1. A is less than the resistance of the ohmmeter
2. B equals the sum of the ohmmeter resistance and the resistance connected to its terminals
3. C is twice the resistance of the ohmmeter
4. D equals the resistance connected between the terminals of the ohmmeter

A milliammeter with a coil resistance of 4 Ω and a maximum coil current of 16 mA is to be converted into an ohmmeter using a dry cell of emf 1.5 V and internal resistance 1.75 Ω. Then:
(1) the standard resistance needed equals ..........

1. A 25 Ω
2. B 43 Ω
3. C 88 Ω
4. D 95 Ω

A milliammeter with a coil resistance of 4 Ω and a maximum coil current of 16 mA is to be converted into an ohmmeter using a dry cell of emf 1.5 V and internal resistance 1.75 Ω. Then:
(2) the external resistance that makes its pointer deflect to 10 mA equals ..........

1. A 311.75 Ω
2. B 150.9 Ω
3. C 112.5 Ω
4. D 56.25 Ω

A milliammeter with a coil resistance of 4 Ω and a maximum coil current of 16 mA is to be converted into an ohmmeter using a dry cell of emf 1.5 V and internal resistance 1.75 Ω. Then:
(3) the current through it if it is connected to an external resistance of 300 Ω equals ..........

1. A $2 \times 10^{-3}$ A
2. B $3.8 \times 10^{-3}$ A
3. C $5 \times 10^{-3}$ A
4. D $6.4 \times 10^{-3}$ A

A galvanometer with a coil resistance of 250 Ω deflects to the end of the scale when a current of 400 μA passes through it. It is connected to a cell of emf 1.5 V with negligible internal resistance, a fixed resistance of 3000 Ω and a variable resistance $R_v$. Then:
(1) the resistance taken from the variable resistance to convert the galvanometer into an ohmmeter equals ..........

1. A 2000 Ω
2. B 1500 Ω
3. C 1000 Ω
4. D 500 Ω

A galvanometer with a coil resistance of 250 Ω deflects to the end of the scale when a current of 400 μA passes through it. It is connected to a cell of emf 1.5 V with negligible internal resistance, a fixed resistance of 3000 Ω and a variable resistance $R_v$. Then:
(2) the resistance which, when connected to the terminals of the ohmmeter, makes the pointer deflect to one quarter of the current scale equals ..........

1. A 3750 Ω
2. B 7500 Ω
3. C 15315 Ω
4. D 11250 Ω

In the opposite figure, a resistance scale has been added to the current scale. If the total internal resistance of the ohmmeter is 3750 Ω and the maximum current on its scale is 400 μA, then:
(1) the resistance $R_1$ equals ..........

1. A 5317 Ω
2. B 3750 Ω
3. C 1250 Ω
4. D 999 Ω

In the opposite figure, a resistance scale has been added to the current scale. If the total internal resistance of the ohmmeter is 3750 Ω and the maximum current on its scale is 400 μA, then:
(2) the resistance $R_2$ equals ..........

1. A 1250 Ω
2. B 2500 Ω
3. C 3750 Ω
4. D 5412 Ω

In the opposite figure, a resistance scale has been added to the current scale. If the total internal resistance of the ohmmeter is 3750 Ω and the maximum current on its scale is 400 μA, then:
(3) the resistance $R_3$ equals ..........

1. A 3750 Ω
2. B 7500 Ω
3. C 9713 Ω
4. D 11250 Ω

In the opposite figure, a resistance scale has been added to the current scale. If the total internal resistance of the ohmmeter is 3750 Ω and the maximum current on its scale is 400 μA, then:
(4) the expected value of the resistance $R_4$ and the reason for it are ..........

1. A value: $\infty$, reason: because the current there is zero
2. B value: $\infty$, reason: because the current there is maximum
3. C value: 0, reason: because the current there is zero
4. D value: 0, reason: because the current there is maximum

The opposite figure shows the components of an ohmmeter. The maximum deflection of the galvanometer pointer was 600 μA when terminals (1) and (2) of the ohmmeter touched each other. If a resistance $R_x$ equal to twice the total resistance of the ohmmeter between its terminals is connected, the reading of the galvanometer pointer equals ..........

1. A 200 μA
2. B 300 μA
3. C 600 μA
4. D 1200 μA

An ohmmeter of total resistance $R_0$ contains a battery of emf $V_B$ with negligible internal resistance. When an unknown resistance R is connected to the terminals of the ohmmeter, its pointer deflects to $\frac{1}{5}$ of the current scale. The resistance of the ohmmeter $(R_0)$ equals ..........

1. A 5 R
2. B $\dfrac{R}{5}$
3. C 4 R
4. D $\dfrac{R}{4}$

If a resistance of 200 Ω makes the ohmmeter pointer deflect to $\frac{1}{2}$ of the current scale, the resistance that makes it deflect to $\frac{1}{3}$ of the current scale is ..........

1. A 300 Ω
2. B 400 Ω
3. C 600 Ω
4. D 1200 Ω

The opposite figure shows equal divisions on the scale of an ohmmeter. If an external resistance is connected between the terminals of the instrument, its pointer deflects to position x on the current scale. This resistance equals .......... the resistance of the ohmmeter.

1. A one third of
2. B half
3. C twice
4. D three times

The opposite figure shows equal divisions on the scale of an ohmmeter. When the instrument is used to measure an unknown resistance R, its pointer deflects to position X on the scale. The external resistance that makes the pointer deflect to position Y on the scale equals ..........

1. A $\dfrac{R}{3}$
2. B 3 R
3. C $\dfrac{R}{9}$
4. D $\dfrac{3R}{4}$

The opposite figure represents equal divisions on the scale of a calibrated ohmmeter, where position y is exactly the middle of the scale. The ratio between the resistances connected between the terminals of the ohmmeter when the pointer settles at positions x and z $\left(\frac{R_x}{R_z}\right)$ is ..........

1. A 4
2. B 9
3. C 16
4. D 25

An ohmmeter consists of an ammeter, a standard resistance and a 6 V battery, and its pointer deflects to the end of the scale when a current of 1 mA passes through it. If an ohm scale is added to the ammeter scale, the correct figure representing the ammeter and ohmmeter scales is ..........

1. A A
2. B B
3. C C
4. D D

The opposite figure shows equal divisions on the scale of an ohmmeter. Using the given data:
(1) the resistance of the ohmmeter is ..........

1. A 9000 Ω
2. B 6000 Ω
3. C 3000 Ω
4. D 1000 Ω

The opposite figure shows equal divisions on the scale of an ohmmeter. Using the given data:
(2) the emf of the cell in the ohmmeter is ..........

1. A 1.5 V
2. B 2 V
3. C 2.5 V
4. D 3 V

An ohmmeter deflects to $\frac{1}{4}$ of the current scale when a 300 Ω resistance is connected to it. The resistance that makes its pointer deflect to $\frac{1}{6}$ of the current scale equals ..........

1. A 1500 Ω
2. B 1000 Ω
3. C 500 Ω
4. D 250 Ω

In the ohmmeter circuit shown, when switch K is closed the pointer becomes ..........

1. A at 2 I
2. B between I and 2 I
3. C at 3 I
4. D between 2 I and 3 I

An ohmmeter was calibrated and its total resistance is $(R_0)$. The opposite graph represents the relation between the reciprocal of the current $\left(\frac{1}{I}\right)$ in the ohmmeter circuit and the external resistance $(R_x)$ connected between the terminals of the ohmmeter. The resistance of the ohmmeter $(R_0)$ equals ..........

1. A $\dfrac{zy}{z-x}$
2. B $\dfrac{xy}{z-x}$
3. C $\dfrac{z-x}{zy}$
4. D $\dfrac{z-x}{xy}$

An ohmmeter was calibrated and its total resistance is $(R_0)$. The opposite graph represents the relation between the reciprocal of the current $\left(\frac{1}{I}\right)$ in the ohmmeter circuit and the external resistance $(R_x)$ connected between the terminals of the ohmmeter. Then:
(1) the emf of the battery used in the ohmmeter equals ..........

1. A 0.5 V
2. B 1 V
3. C 1.5 V
4. D 2 V

An ohmmeter was calibrated and its total resistance is $(R_0)$. The opposite graph represents the relation between the reciprocal of the current $\left(\frac{1}{I}\right)$ in the ohmmeter circuit and the external resistance $(R_x)$ connected between the terminals of the ohmmeter. Then:
(2) the resistance of the ohmmeter $(R_0)$ equals ..........

1. A 2 kΩ
2. B 4 kΩ
3. C 6 kΩ
4. D 8 kΩ

In a moving-coil galvanometer, explain:
(1) When a current passes, the galvanometer pointer is deflected and then settles at a certain reading.
(2) When the current is cut off, the galvanometer pointer returns to zero.

State two features considered when making a moving-coil galvanometer to make its scale uniform.

Give a reason: the magnetic torque acting on a galvanometer coil carrying a current I does not change while the coil rotates.

A moving-coil galvanometer has a scale divided into 20 divisions, each division indicating 200 microamperes. Calculate the current needed to make the galvanometer pointer deflect to one quarter of its scale.

Why is the galvanometer reading of the current in a circuit always less than the current when the galvanometer is not part of the circuit?

A galvanometer with a maximum scale reading of $20\ \mu A$ is connected in a circuit as in the figure:
(1) Explain why the galvanometer is not suitable for measuring the current in this circuit when the switch is closed.
(2) Suggest a way to make the galvanometer suitable for measuring the current in this circuit.

A galvanometer with a coil resistance of $30\ \Omega$ and a maximum measurable current of 0.01 A is to be converted into an ammeter. Calculate the shunt resistance needed so that the ammeter measures a maximum current of 1 A, and the total resistance of the ammeter in this case.

A galvanometer of resistance $R_g$ and maximum scale reading $I_g$ is connected to a shunt $R_s$, so the total resistance of the instrument becomes $\frac{R_g}{4}$ and the maximum current it measures becomes I. Find the ratio between:
(1) the two resistances $(\frac{R_s}{R_g})$.
(2) the two currents $(\frac{I}{I_g})$.

A sensitive galvanometer can have its coil connected to several shunt resistances, each separately. The opposite graph represents the relation between the maximum current the ammeter can measure (I) and the reciprocal of the shunt resistance $(\frac{1}{R_s})$. Calculate:
(1) the maximum current the galvanometer can measure $(I_g)$.
(2) the resistance of the galvanometer $(R_g)$.
(3) the shunt resistance needed to make the ammeter measure a maximum current of 0.3 A

A galvanometer is converted into an ammeter whose range reaches 0.06 A when connected to a shunt of resistance $R_s$, and 0.03 A when connected to a shunt of resistance $4 R_s$. What is the greatest current the galvanometer can measure without a shunt?

A moving-coil galvanometer of resistance $R_g$ has a scale divided into five divisions, each indicating 0.01 A. It is connected to a shunt of resistance $0.2 R_g$ and included in a circuit, and its pointer deflects as in the opposite figure. Calculate:
(1) the current I in the circuit.
(2) the maximum current the ammeter can measure.

An ammeter has a resistance of $24\ \Omega$. Calculate the shunt needed to reduce the sensitivity of the ammeter to $\frac{1}{9}$ of its value.

In the opposite figure, when switch $K_1$ is closed, the sensitivity of the instrument becomes half the sensitivity of the galvanometer. Calculate the ratio of the sensitivity of the instrument to that of the galvanometer when only switch $K_2$ is closed.

The opposite figure shows the structure of an ammeter. What happens when switch K is closed to:
(1) the resistance of the ammeter?
(2) the maximum current the ammeter can measure?
(3) the accuracy of the ammeter?
(4) the sensitivity of the ammeter?

In the opposite figure, a galvanometer of resistance $50\ \Omega$ is connected in a circuit:
(1) What is the maximum reading of the galvanometer?
(2) How is it converted into an ammeter measuring a maximum current of 0.6 A?

The following figure shows the position of the pointer of a galvanometer of resistance R connected to a shunt of resistance 0.5 R and included in a circuit. Deduce the position of the pointer when switch K is closed.

The opposite figure represents an instrument that measures a maximum potential difference of 1 V with switch (K) open. What is the maximum potential difference the instrument measures when switch K is closed?

Explain: a voltmeter is connected in parallel across the conductor whose potential difference is to be measured.

Write the mathematical relation represented by the graph and what the slope of the straight line equals for each of the following:
where: (θ) is the deflection angle of the galvanometer pointer, (I) the current, (V) the potential difference, $(V_g)$ the maximum potential difference across the galvanometer, $(R_m)$ the multiplier resistance, $(R_s)$ the shunt resistance, $(I_g)$ the maximum current the galvanometer coil can carry.

In the opposite circuit, compare the total current and the potential difference across the $10\ \Omega$ resistance before and after connecting a voltmeter of resistance $190\ \Omega$ across points a and b, explaining your answer.

The opposite figure shows a voltmeter consisting of a galvanometer of resistance $R_g$, two multiplier resistances R and 2 R, and a two-way switch that can connect either of them to the galvanometer. State which of the two multipliers gives the voltmeter:
(1) a greater range.
(2) a greater accuracy in measuring potential difference.
(3) a greater sensitivity.

In the opposite figure, a galvanometer measures a maximum potential difference $V_g$. When only switch $K_1$ is closed, the instrument can measure a maximum potential difference of $7 V_g$, and when both switches $K_1$ and $K_2$ are closed, it can measure a maximum potential difference of $3 V_g$. Find the ratio of the two resistances $(\frac{(R_m)_1}{(R_m)_2})$.

In an ohmmeter:
(1) Why must the emf of the cell be constant?
(2) Suppose the emf of the cell has decreased below its standard value. State, with explanation, what you notice when the two terminals of the ohmmeter are connected together.

Compare, with explanation, between the scales of a microammeter and an ohmmeter (in terms of: uniformity of the scale).

The opposite figure represents equal divisions on the scale of an ohmmeter consisting of a galvanometer, a standard resistance and a cell of emf 2 V with negligible internal resistance. Calculate:
(1) the maximum reading on the galvanometer scale $(I_g)$.
(2) the external resistance which, connected to the terminals of the ohmmeter, makes its pointer deflect to mark (x) on its scale.

An ohmmeter of resistance $R_0$ contains a cell of emf $V_B$. If its terminals are connected to a resistance $R_x$, a current I passes in its circuit. Prove that: $R_x = \frac{V_B}{I} - R_0$

The opposite graph represents the relation between the current (I) in an ohmmeter and the external resistance $(R_x)$ connected to its terminals. Find:
(1) the maximum current that can pass through the ohmmeter.
(2) the resistance of the ohmmeter.
(3) the resistance $R_x$ which, when connected to the terminals of the ohmmeter, makes the current through it $50\ \mu A$

You have two galvanometers (1) and (2). A current (I) passes through each of them; the pointer of galvanometer (1) deflects from zero through 30°, and the pointer of galvanometer (2) deflects from zero through an angle ten degrees greater than that of galvanometer (1). Which of the following statements is correct after the current is increased to 2 I in each of them? (1st session 2024)

1. A The deflection angle of the pointer of galvanometer (1) from zero equals 20°
2. B The sensitivity of galvanometer (1) is $\frac{60}{I}$
3. C The sensitivity of galvanometer (2) is $\frac{40}{I}$
4. D The deflection angle of the pointer of galvanometer (2) from zero equals 40°

The following figures show the deflection angles of the pointers of four galvanometers when different currents pass through them. Which two galvanometers have the same sensitivity? (2nd session 2024)

1. A (1), (3)
2. B (1), (4)
3. C (2), (4)
4. D (3), (4)

The opposite figure shows a diagram of two deflection angles of the pointer of a moving-coil galvanometer in two DC circuits carrying currents $I_1$ and $I_2$. The ratio $(\frac{I_1}{I_2})$ equals .......... (Sample exam 2025)

1. A $\frac{1}{2}$
2. B $\frac{1}{3}$
3. C $\frac{2}{1}$
4. D $\frac{3}{1}$

You have an old sensitive galvanometer in the lab with a full-scale reading of $200\ \mu A$. When a current of $50\ \mu A$ is passed through its coil, its pointer points to $60\ \mu A$. Which of the following has probably happened to the galvanometer due to frequent use? (Sample exam 2025)

1. A The permeability of the iron cylinder decreased
2. B The spiral springs were damaged
3. C The friction with the agate bearing increased
4. D The magnetic field of the magnet became weaker

In a moving-coil galvanometer, every 5 divisions indicate a current of 1 mA and every 20 divisions indicate a potential difference of 1 V. The resistance of the galvanometer equals .......... (Sample exam 2025)

1. A $250\ \Omega$
2. B $500\ \Omega$
3. C $40\ \Omega$
4. D $25\ \Omega$

Which of the following figures shows the scale of the galvanometer with the highest sensitivity, given that the angle between the two ends of each scale is the same? (1st session 2025)

1. A A
2. B B
3. C C
4. D D

Two galvanometers X and Y are connected in series in a circuit. When a current passes in the circuit, the deflection of the pointer of galvanometer (X) is observed to be greater than that of galvanometer (Y). If the coils of the two instruments are identical, which of the following statements explains this observation? (2nd session 2025)

1. A The magnetic dipole moment of the coil of galvanometer (X) is greater
2. B The friction of the pivot of the coil of galvanometer (X) with the base is greater
3. C The current through the coil of galvanometer (X) is greater
4. D The magnet used in galvanometer (X) is stronger

A sensitive galvanometer with a coil resistance of $15\ \Omega$ is connected to different shunts to convert it into an ammeter with a different range each time. Which of the following figures represents the ammeter with the greatest range? (Trial exam / May 2021)

1. A A
2. B B
3. C C
4. D D

The opposite graph represents the relation between the maximum current measured by the ammeter and the reciprocal of the shunt resistance. The maximum potential difference across the shunt equals .......... (Trial exam / June 2021)

1. A 0.1 V
2. B 0.8 V
3. C 1.2 V
4. D 1 V

The opposite graph represents the relation between the maximum current measured by an ammeter and the reciprocal of the shunt resistance. The resistance of the galvanometer $(R_g)$ equals .......... (1st session 2021)

1. A $20\ \Omega$
2. B $40\ \Omega$
3. C $80\ \Omega$
4. D $100\ \Omega$

A galvanometer with a coil resistance $R_g$ measures a maximum current $I_g$. When its coil is connected to a shunt of resistance $R_1$, the sensitivity of the instrument decreases to $\frac{3}{4}$ of its original value, and when $R_1$ is replaced by another shunt of resistance $R_2$, the sensitivity decreases to $\frac{3}{8}$ of its original value. The ratio of the shunt resistance $R_1$ to the shunt resistance $R_2$ equals .......... (2nd session 2021)

1. A 2
2. B 3
3. C 4
4. D 5

A galvanometer with a coil resistance $R_g$ measures a maximum current $I_g$. When a shunt R is used, the greatest measurable current becomes $4 I_g$. When the shunt is replaced by another of 3 R, the greatest measurable current becomes .......... (1st session 2022)

1. A $1.5 I_g$
2. B $3 I_g$
3. C $2.5 I_g$
4. D $2 I_g$

The two graphs express the relation between the maximum measurable current in two different ammeters and the reciprocal of a variable resistance $(\frac{1}{R_s})$ acting as the shunt in each. The ratio of the galvanometer resistance in the first ammeter to that in the second ammeter $(\frac{(R_g)_1}{(R_g)_2})$ equals .......... (2nd session 2022)

1. A $\frac{1}{3}$
2. B $\frac{2}{1}$
3. C $\frac{3}{1}$
4. D $\frac{1}{2}$

The figure represents a sensitive galvanometer. Which of the figures represents converting the galvanometer into an ammeter with a maximum current of 1 A? (Trial exam 2023)

1. A A
2. B B
3. C C
4. D D

In the opposite figure, if the shunt is changed so that the sensitivity of the instrument increases with the same current (I) passing, which of the following ratios increases? (1st session 2023)

1. A $\frac{I_g}{I_s}$
2. B $\frac{V_g}{V_s}$
3. C $\frac{R_g}{R_t}$
4. D $\frac{R_g}{R_s}$

The opposite table records different values of shunt resistance $R_s$, each connected separately to the same galvanometer to obtain a DC ammeter in each of the cases Z, Y, X and W. What is the correct order of these cases according to the sensitivity of the instrument? (2nd session 2023)

1. A $Y > W > X > Z$
2. B $X > Z > W > Y$
3. C $Y > W > Z > X$
4. D $W > Y > Z > X$

A galvanometer of resistance $(R_g)$ was connected to a shunt of $(\frac{1}{2} R_g)$, then the galvanometer was connected again to a shunt of $(\frac{1}{4} R_g)$. The ratio of the sensitivity of the ammeter in the first case to that in the second case equals .......... (1st session 2024)

1. A $\frac{1}{5}$
2. B $\frac{3}{5}$
3. C $\frac{1}{3}$
4. D $\frac{5}{3}$

A galvanometer has a resistance of $60\ \Omega$. The shunt that reduces the sensitivity of the instrument to one sixth equals .......... (2nd session 2024)

1. A $24\ \Omega$
2. B $6\ \Omega$
3. C $3\ \Omega$
4. D $12\ \Omega$

A microammeter has a coil resistance of $100\ \Omega$ and a maximum coil current of $100\ \mu A$. Its range can be increased to 0.1 A by connecting it to a shunt of .......... (Sample exam 2025)

1. A $0.5\ \Omega$
2. B $0.1\ \Omega$
3. C $0.05\ \Omega$
4. D $0.01\ \Omega$

A galvanometer with a coil resistance of $100\ \Omega$ has a scale divided into N divisions. If a current I passes through it, its pointer deflects to the end of its scale. When a resistance of $20\ \Omega$ is connected in parallel with the galvanometer coil to convert it into an ammeter and the same current I passes through the ammeter, its pointer deflects to only two divisions. The number of divisions on the galvanometer scale (N) equals .......... (Sample exam 2025)

1. A 2
2. B 6
3. C 12
4. D 24

In the figure, if switch K is closed, the sensitivity of the galvanometer decreases to one fifth. The values of $R_s$ and $V_B$ respectively are .......... (Sample exam 2025)

1. A $40\ \Omega$ , 100 V
2. B $100\ \Omega$ , 60 V
3. C $50\ \Omega$ , 100 V
4. D $40\ \Omega$ , 60 V

The graph represents the relation between the maximum range of two ammeters (I) and the reciprocal of the shunt $(\frac{1}{R_s})$ connected to the galvanometer coil in each. The ratio between the resistances of the two galvanometers $\frac{(R_g)_1}{(R_g)_2}$ equals .......... (Sample exam 2025)

1. A $\frac{1}{2}$
2. B $\frac{2}{1}$
3. C $\frac{1}{3}$
4. D $\frac{3}{1}$

An ammeter of resistance (R) consists of a galvanometer of resistance $45\ \Omega$ and a shunt $(R_s)$. If the current in the galvanometer is $\frac{1}{5}$ of the current in the shunt, what is the resistance of the ammeter (R)? (1st session 2025)

1. A $9\ \Omega$
2. B $7.5\ \Omega$
3. C $10\ \Omega$
4. D $15\ \Omega$

An ammeter consists of a galvanometer of resistance $(R_g)$ and full-scale reading $(I_g)$, and a variable resistance $(R_s)$ acting as a shunt. The opposite graph represents the relation between the maximum current (I) the ammeter measures and the reciprocal of the shunt resistance $(\frac{1}{R_s})$. What is the potential difference across the galvanometer when its pointer deflects to the end of the scale? (2nd session 2025)

1. A 0.5 V
2. B 5000 V
3. C 5 V
4. D $5 \times 10^{-3}\ V$

The opposite figure represents a galvanometer (G) converted into an ammeter. If the resistance of the galvanometer is $(R_g = 18\ \Omega)$, the ratio between the sensitivity of the instrument before and after closing switches $K_1$ and $K_2$ equals .......... (Sample exam 2026)

1. A $\frac{2}{5}$
2. B $\frac{5}{2}$
3. C $\frac{7}{4}$
4. D $\frac{4}{7}$

Three galvanometers, each with a coil resistance $R_g$, are connected to three multipliers to convert them into three voltmeters A, B and C as in the following figures. The order of the maximum reading of each instrument is .......... (Trial exam / June 2021)

1. A $V_B > V_A > V_C$
2. B $V_A < V_C < V_B$
3. C $V_C > V_B > V_A$
4. D $V_C < V_B < V_A$

A galvanometer with a coil resistance of $50\ \Omega$ is connected to a multiplier of $450\ \Omega$, and its maximum reading is 1 V. When the galvanometer is connected to a multiplier $(R_m)_2$, the maximum voltmeter reading is 18 V. The value of $(R_m)_2$ is .......... (1st session 2021)

1. A $9000\ \Omega$
2. B $8950\ \Omega$
3. C $9050\ \Omega$
4. D $9500\ \Omega$

A galvanometer measures a maximum potential difference of 0.1 V when a maximum current of 2 mA passes, and each division indicates 0.01 V. When it is connected to a multiplier of $450\ \Omega$, each division indicates .......... (2nd session 2021)

1. A 0.01 V
2. B 1 V
3. C 0.1 V
4. D 0.001 V

A galvanometer with a maximum potential difference of 1 V across its coil is connected to a multiplier to convert it into a voltmeter several different times. The graph in front of you represents the relation between the maximum potential difference measured by the voltmeter (V) and the total resistance of the voltmeter $(R_g + R_m)$. The resistance of the galvanometer $(R_g)$ equals .......... (1st session 2022)

1. A $100\ \Omega$
2. B $1000\ \Omega$
3. C $500\ \Omega$
4. D $50\ \Omega$

A voltmeter has a resistance of $100\ \Omega$ and can measure a maximum potential difference of 1 V. The multiplier that must be connected to increase the measured potential difference by 10 times equals .......... (2nd session 2022)

1. A $0.9\ k\Omega$
2. B $10\ k\Omega$
3. C $1.1\ k\Omega$
4. D $1\ k\Omega$

A voltmeter has a resistance of $40\ \Omega$. When a current of 0.1 A passes through it, its pointer reaches the end of its scale. The multiplier that makes the maximum potential difference it measures 100 V is .......... (Trial exam 2023)

1. A $25\ \Omega$
2. B $2.5\ \Omega$
3. C $960\ \Omega$
4. D $1040\ \Omega$

A galvanometer with a full-scale reading of 0.01 A is connected in series with a $2000\ \Omega$ resistance to convert it into a voltmeter, as in the figure, and the maximum potential difference measured by the voltmeter is 20.5 V. For the maximum potential difference measured by the instrument to become 10.25 V, the $2000\ \Omega$ resistance must be replaced by a resistance of .......... (1st session 2023)

1. A $1025\ \Omega$
2. B $1000\ \Omega$
3. C $975\ \Omega$
4. D $4000\ \Omega$

According to the data shown in the figure, the potential difference measured by the voltmeter is .......... (2nd session 2023)

1. A 50 V
2. B 100 V
3. C 20 V
4. D 10 V

A voltmeter has a total resistance of $1200\ \Omega$ and can withstand a maximum potential difference of 3 V. If it is connected to a multiplier $(R_m)$, the maximum potential difference it can withstand becomes 10 V. The value of the multiplier $(R_m)$ equals .......... (Sample exam 2025)

1. A $1800\ \Omega$
2. B $2400\ \Omega$
3. C $2800\ \Omega$
4. D $4000\ \Omega$

A moving-coil galvanometer with a coil resistance $R_g$ can withstand a maximum potential difference $V_g$. When the galvanometer is connected to a resistance R in series with its coil, it becomes a voltmeter of range $V_1$, and when the same galvanometer is connected to a resistance 2 R in series with its coil, it becomes a voltmeter of range $V_2$. Then .......... (Sample exam 2025)

1. A $V_2 = V_1 - 2 V_g$
2. B $V_2 = 2 V_1 - V_g$
3. C $V_2 = 2 V_1 + V_g$
4. D $V_2 = 2 V_1$

A moving-coil galvanometer has 15 divisions. If every 5 divisions indicate 5 mA and every two divisions indicate 10 mV, the resistance that must be connected in series with the galvanometer coil so that each division indicates 1 V is .......... (Sample exam 2025)

1. A $995\ \Omega$
2. B $99.5\ \Omega$
3. C $9.95\ \Omega$
4. D $9950\ \Omega$

A voltmeter consists of a galvanometer of resistance $50\ \Omega$ and a multiplier of resistance $2950\ \Omega$. When the voltmeter is connected across a battery of emf 3 V with negligible internal resistance, as shown in the figure, its pointer deflects to the end of its scale. When a resistance (R) is connected with the multiplier inside the voltmeter while it is connected to the battery terminals, its pointer deflects to the middle of its scale. What is the resistance (R) and how is it connected? (1st session 2025)

1. A $1500\ \Omega$, in series
2. B $3000\ \Omega$, in parallel
3. C $1500\ \Omega$, in parallel
4. D $3000\ \Omega$, in series

An ohmmeter is connected to an external resistance (x) of $400\ \Omega$ and the pointer deflects to $\frac{3}{4}$ of the galvanometer scale. When resistance (x) is replaced by another (y) of $6000\ \Omega$, the pointer deflects to .......... of the galvanometer scale. (Trial exam / May 2021)

1. A $\frac{1}{6}$
2. B $\frac{3}{5}$
3. C $\frac{1}{5}$
4. D $\frac{5}{6}$

An ohmmeter contains a galvanometer with a full-scale reading $I_g$. When an external resistance of $12\ k\Omega$ is connected between the terminals of the ohmmeter, the current becomes $\frac{1}{5} I_g$. When the ohmmeter is connected to an external resistance of $1.5\ k\Omega$, the current becomes .......... (Trial exam / June 2021)

1. A $\frac{2}{3} I_g$
2. B $\frac{1}{8} I_g$
3. C $\frac{1}{5} I_g$
4. D $\frac{3}{4} I_g$

The opposite figure represents the reading of the galvanometer inside an ohmmeter. When a resistance R is connected between the terminals of the ohmmeter, the pointer deflects to $\frac{1}{3} I_g$. The resistance of the ohmmeter equals .......... (1st session 2021)

1. A 0.5 R
2. B R
3. C 2 R
4. D 3 R

The opposite figure shows equal divisions on the galvanometer scale in an ohmmeter circuit. The value of $R_x$ shown in the figure equals .......... (2nd session 2021)

1. A $6000\ \Omega$
2. B $18000\ \Omega$
3. C $12000\ \Omega$
4. D $10000\ \Omega$

An ohmmeter contains a galvanometer with a full-scale reading $I_g$. When an external resistance of $50\ k\Omega$ is connected between the terminals of the ohmmeter, the current through it becomes $\frac{1}{3} I_g$. The external resistance that makes the current in the ohmmeter $\frac{3}{4} I_g$ equals .......... (1st session 2022)

1. A $\frac{25}{3}\ k\Omega$
2. B $\frac{225}{2}\ k\Omega$
3. C $\frac{50}{3}\ k\Omega$
4. D $\frac{50}{4}\ k\Omega$

An ohmmeter contains a galvanometer with a full-scale reading $I_g$. When an external resistance (R) is connected between the terminals of the ohmmeter, the current through it becomes $\frac{3}{4} I_g$, and when resistance (R) is replaced by another of (3 R), the current becomes .......... (2nd session 2022)

1. A $\frac{1}{4} I_g$
2. B $\frac{1}{3} I_g$
3. C $\frac{4}{9} I_g$
4. D $\frac{1}{2} I_g$

Four resistances are connected together as in the figure. The ohmmeter pointer shows the same reading when its terminals are connected to .......... (Trial exam 2023)

1. A points (c), (b) or points (b), (d)
2. B points (a), (c) or points (a), (d)
3. C points (a), (c) or points (b), (d)
4. D points (a), (d) or points (c), (d)

An ohmmeter of total resistance $3000\ \Omega$ has its pointer deflect through an angle θ to reach the end of the current scale when its terminals touch each other. When its terminals are connected to a resistance $R_1$, the pointer deflects through $\frac{\theta}{3}$ from the zero of the current scale, and when $R_1$ is replaced by another resistance $R_2$, the pointer deflects through $\frac{\theta}{4}$ from the zero of the current scale. The values of $R_1$ and $R_2$ respectively are .......... (Trial exam 2023)

1. A $3000\ \Omega$ , $9000\ \Omega$
2. B $6000\ \Omega$ , $12000\ \Omega$
3. C $3000\ \Omega$ , $12000\ \Omega$
4. D $6000\ \Omega$ , $9000\ \Omega$

In the ohmmeter circuit shown, when another resistance is connected in series with the unknown resistance $(R_x)$, the pointer deflects to $\frac{3}{5}$ of the galvanometer scale. The other resistance connected equals .......... (1st session 2023)

1. A $6 R_x$
2. B $5 R_x$
3. C $\frac{2}{3} R_x$
4. D $3 R_x$

The opposite figure shows an ohmmeter circuit containing a galvanometer of coil resistance $(R_g)$. When an external resistance $(R_x)$ equal to $15 R_g$ is connected to the terminals of the ohmmeter, the galvanometer pointer deflects to $\frac{1}{5}$ of the current scale. The resistance taken from the rheostat $(R_v)$ equals .......... (2nd session 2023)

1. A $3.75 R_g$
2. B $0.75 R_g$
3. C $0.25 R_g$
4. D $3.25 R_g$

The figure shows equal spaces on the scale of an ohmmeter. When a resistance (R) is connected between the terminals of the ohmmeter, its pointer deflects to position (x). When another resistance is connected to resistance (R) between the terminals of the ohmmeter, its pointer deflects to position (z). The resistance connected to resistance (R) equals .......... (1st session 2025)

1. A 9 R
2. B 2 R
3. C 8 R
4. D 3 R

An ohmmeter of resistance R has its terminals connected to an external resistance R and two switches $K_1$ and $K_2$ as shown in the figure. The ohmmeter pointer settles at the mark (∞) on the resistance scale when .......... (2nd session 2025)

1. A both switches are closed
2. B both switches are open
3. C switch $K_1$ is open and switch $K_2$ is closed
4. D switch $K_1$ is closed and switch $K_2$ is open