Transistors, Digital and Analog Electronics questions

The base region in a transistor is ..........

1. A thick, with a high impurity concentration
2. B thin, with a high impurity concentration
3. C thick, with a low impurity concentration
4. D thin, with a low impurity concentration

In a pnp transistor, the majority charge carriers in both the emitter and the collector are ..........

1. A acceptor ions
2. B donor ions
3. C free electrons
4. D holes

An npn transistor is made of ..........

1. A one diode junction
2. B two diode junctions
3. C three diode junctions
4. D four diode junctions

The two opposite figures (1) and (2) show a transistor connected in a common emitter circuit. In which of them is it used as a switch in the (off) state?

1. A Figure (1)
2. B Figure (2)
3. C Both figures
4. D Neither of them

In a transistor, the ratio of the impurity concentration in the emitter to that in the collector is ..........

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

When a transistor is connected in common base, if the distribution ratio is $\alpha_e$ and the amplification ratio is $\beta_e$, then ..........

1. A $\alpha_e < 1$
2. B $\beta_e > 1$
3. C $\alpha_e = \dfrac{\beta_e}{1 + \beta_e}$
4. D all of the above

In a common emitter npn transistor circuit, if the base is given a large positive voltage, the transistor works ..........

1. A as a half-wave rectifier
2. B as a closed switch
3. C as an open switch
4. D as a full-wave rectifier

In an npn transistor, if the collector current is 18 mA and it is 90% of the emitter current, the emitter current $(I_E)$ and the base current $(I_B)$ respectively are ..........

1. A 20 mA, 2 mA
2. B 30 mA, 12 mA
3. C 19 mA, 1 mA
4. D 20 mA, 4 mA

The opposite graph shows the relation between the collector current $(I_C)$ and the base current $(I_B)$ of a pnp transistor:
(1) The value of $\alpha_e$ is ..........

1. A 0.96
2. B 0.98
3. C 0.99
4. D 1

The opposite graph shows the relation between the collector current $(I_C)$ and the base current $(I_B)$ of a pnp transistor:
(2) The emitter current when $I_C$ = 45 mA is ..........

1. A 20.12 mA
2. B 30.15 mA
3. C 40.25 mA
4. D 45.45 mA

The opposite graph shows the relation between the collector current $(I_C)$ and the emitter current $(I_E)$ of an npn transistor. The values of $\alpha_e$ and $\beta_e$ respectively are ..........

1. A $\alpha_e$: 0.96, $\beta_e$: 24
2. B $\alpha_e$: 0.96, $\beta_e$: 48
3. C $\alpha_e$: 0.49, $\beta_e$: 32
4. D $\alpha_e$: 0.49, $\beta_e$: 64

If $\alpha_e$ of a transistor is 0.99 and the base current is 100 μA, the amplification factor $(\beta_e)$ and the collector current $(I_C)$ respectively are ..........

1. A $\beta_e$: 98, $I_C$: $9.8 \times 10^{-3}$ A
2. B $\beta_e$: 99, $I_C$: $9.9 \times 10^{-3}$ A
3. C $\beta_e$: 99, $I_C$: 9.9 A
4. D $\beta_e$: 98, $I_C$: 9.8 A

If the base current of a transistor is 24 μA and its amplification factor is 24, the distribution constant $(\alpha_e)$ and the collector current $(I_C)$ respectively are ..........

1. A $\alpha_e$: 0.76, $I_C$: $576 \times 10^{-3}$ A
2. B $\alpha_e$: 0.76, $I_C$: $576 \times 10^{-6}$ A
3. C $\alpha_e$: 0.96, $I_C$: $576 \times 10^{-3}$ A
4. D $\alpha_e$: 0.96, $I_C$: $576 \times 10^{-6}$ A

When the transistor is used as an amplifier, if the electric signal going to its base is 200 μA and the collector current is 10 mA, then $\beta_e$ and $\alpha_e$ respectively are ..........

1. A $\beta_e$: 20, $\alpha_e$: 0.95
2. B $\beta_e$: 20, $\alpha_e$: 0.98
3. C $\beta_e$: 50, $\alpha_e$: 0.95
4. D $\beta_e$: 50, $\alpha_e$: 0.98

If the amplification ratio of an npn transistor is 99 and the collector current is 10 mA, the distribution ratio $(\alpha_e)$ and the emitter current $(I_E)$ respectively are ..........

1. A $\alpha_e$: 0.98, $I_E$: $10.1 \times 10^{-3}$ A
2. B $\alpha_e$: 0.98, $I_E$: $0.1 \times 10^{-3}$ A
3. C $\alpha_e$: 0.99, $I_E$: $0.1 \times 10^{-3}$ A
4. D $\alpha_e$: 0.99, $I_E$: $10.1 \times 10^{-3}$ A

In a transistor circuit, $(V_{CC} = 1.5\ V)$, the potential difference between the collector and the emitter is $(V_{CE} = 0.5\ V)$ and the collector circuit resistance is $(R_C = 500\ \Omega)$. The collector current $(I_C)$ is ..........

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

In the opposite transistor circuit, when the resistance $R_1$ is increased, the voltmeter reading ..........

1. A increases
2. B decreases but does not reach zero
3. C stays constant
4. D equals zero

The circuit that shows the correct way of connecting the batteries in a common emitter transistor circuit used as a closed switch is ..........

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

In the transistor circuit shown in the figure, the transistor is connected ..........

1. A as an open switch
2. B in common emitter
3. C in common base
4. D cannot be determined

The figure shows an npn transistor circuit. From the given data, the values of the two constants $\beta_e$ and $\alpha_e$ respectively are ..........

1. A $\beta_e$: 50, $\alpha_e$: 0.98
2. B $\beta_e$: 49, $\alpha_e$: 0.99
3. C $\beta_e$: 49, $\alpha_e$: 0.98
4. D $\beta_e$: 50, $\alpha_e$: 0.99

The opposite figure shows an npn transistor circuit. The distribution ratio $(\alpha_e)$ equals ..........

1. A 0.92
2. B 0.95
3. C 0.96
4. D 0.98

The opposite figure shows a circuit using the transistor as a switch. If the potential difference across the base resistor $R_B$ is 0.01 V and $\beta_e = 75$, then ..........

1. A base current $(I_B)$: $3.33 \times 10^{-6}$ A, output voltage $(V_{CE})$: 0.55 V
2. B base current $(I_B)$: $3.33 \times 10^{-6}$ A, output voltage $(V_{CE})$: 0.75 V
3. C base current $(I_B)$: $6.67 \times 10^{-6}$ A, output voltage $(V_{CE})$: 0.55 V
4. D base current $(I_B)$: $6.67 \times 10^{-6}$ A, output voltage $(V_{CE})$: 0.75 V

The opposite figure shows an (npn) transistor circuit in the closed (on) state. When the resistance taken from the rheostat (S) is increased, the values of the potential differences $V_1$ and $V_2$ respectively ..........

1. A decrease, decrease
2. B decrease, increase
3. C increase, increase
4. D increase, decrease

From the opposite figure, the value of $I_E$ is ..........

1. A $2 \times 10^{-3}$ A
2. B $2.02 \times 10^{-3}$ A
3. C $2 \times 10^{-5}$ A
4. D $2.02 \times 10^{-5}$ A

In an npn transistor, if the difference between the collector and base currents $(I_C - I_B)$ is 97 mA and the emitter current $(I_E)$ is 99 mA, the amplification factor $(\beta_e)$ equals ..........

1. A 97
2. B 98
3. C 99
4. D 100

In the transistor circuit shown in figure (1), the relation between the ammeter reading $(I_C)$ and the voltmeter reading $(V_{CE})$ was plotted as in figure (2). The values of $R_C$ and $V_{CC}$ respectively are ..........

1. A $R_C$: 1 kΩ, $V_{CC}$: 4 V
2. B $R_C$: 1 kΩ, $V_{CC}$: 5 V
3. C $R_C$: 2 kΩ, $V_{CC}$: 4 V
4. D $R_C$: 2 kΩ, $V_{CC}$: 5 V

Which of the following curves shows how the voltage (V) of an electric signal in a digital electronic device changes with time (t)?

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

To send and receive signals carrying information in digital electronics, converter (1) is used when sending and converter (2) is used when receiving, so ..........

1. A converter (1): analog to digital, converter (2): analog to digital
2. B converter (1): analog to digital, converter (2): digital to analog
3. C converter (1): digital to analog, converter (2): analog to digital
4. D converter (1): digital to analog, converter (2): digital to analog

Which of the following choices correctly shows the order of the stages of digital sending and receiving?

1. A physical quantity → analog signal → digital signal → analog signal → physical quantity
2. B physical quantity → digital signal → analog signal → digital signal → physical quantity
3. C analog signal → physical quantity → digital signal → physical quantity → analog signal
4. D digital signal → analog signal → physical quantity → analog signal → digital signal

The binary number equivalent to the decimal number 20 is ..........

1. A $(10101)_2$
2. B $(10100)_2$
3. C $(11100)_2$
4. D $(00111)_2$

The binary number equivalent to the sum of the decimal numbers (1 + 1 + 1 + 1) is ..........

1. A $(1111)_2$
2. B $(101)_2$
3. C $(110)_2$
4. D $(100)_2$

The decimal number equivalent to the binary number $(1010)_2$ is ..........

1. A 4
2. B 8
3. C 10
4. D 12

For the opposite logic gate, the probability that the output is (1) equals ..........

1. A 10%
2. B 20%
3. C 50.9%
4. D 87.5%

The opposite figure shows a logic gate. The number of cases in which the output is (High) equals ..........

1. A 0
2. B 1
3. C 2
4. D 3

For the logic gates shown, so that the output is Y = 1, the input values A, B, C needed are ..........

1. A A: 0, B: 1, C: 0
2. B A: 0, B: 0, C: 1
3. C A: 1, B: 0, C: 1
4. D A: 1, B: 0, C: 0

Which of the following logic circuits satisfies the opposite truth table?

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

The electric signal $(11001)_2$ was fed to the input of an inverter gate. The output signal is ..........

1. A $(00111)_2$
2. B $(00110)_2$
3. C $(10101)_2$
4. D $(11001)_2$

In the opposite logic circuit, if the input is as shown in the opposite table, the output is ..........

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

In the logic circuit shown in the figure, which of the following inputs makes the output D = 1?

1. A A: 0, B: 0, C: 1
2. B A: 1, B: 0, C: 1
3. C A: 1, B: 0, C: 0
4. D A: 0, B: 1, C: 1

The opposite figure shows a network of logic gates and its truth table. The logic gate G is a(n) .......... gate.

1. A AND
2. B OR
3. C NOT
4. D AND or OR

The opposite figure shows a logic circuit. If its output is (1) when the input on A, B is (0, 0), then the gates X and Y respectively are ..........

1. A gate X: OR, gate Y: AND
2. B gate X: NOT, gate Y: AND
3. C gate X: NOT, gate Y: NOT
4. D gate X: NOT, gate Y: OR

The opposite figure shows a network of logic gates and its truth table. The gates X and Y are ..........

1. A gate X: OR, gate Y: AND
2. B gate X: AND, gate Y: AND
3. C gate X: OR, gate Y: OR
4. D gate X: AND, gate Y: OR

The opposite figure shows a logic circuit, and the truth table after it shows some input and output values of this circuit. The values of x, y, z in the table are ..........

1. A x: 0, y: 0, z: 0
2. B x: 1, y: 0, z: 0
3. C x: 0, y: 0, z: 1
4. D x: 0, y: 1, z: 1

Which of the following logic circuits satisfies the opposite truth table?

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

In the electric circuit shown in the opposite figure, the two switches (A) and (B) are the inputs of a logic gate and the lamp (C) is its output. The correct truth table of this gate is ..........

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

Which of the following logic gates represents the opposite electric circuit?

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

In which of the following logic gates is the output a decimal number equal to 11 when the opposite input table is used?

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

The opposite figure shows the regions of an npn transistor. Explain what happens to the free electrons in each region when it is connected as in the figure.

Give a reason: in a transistor, the distribution constant $(\alpha_e)$ is close to one, while the amplification ratio $(\beta_e)$ is greater than one.

Compare between the emitter and the collector of an npn transistor connected in a common base circuit (in terms of: the valency of the impurity atoms - the type of connection with the base - the barrier voltage with the base).

Write the mathematical relation between the two variables in the opposite graph, and state what the slope of the straight line equals.

What conditions must an npn transistor meet to work as a closed (on) switch?

A transistor was connected to an ohmmeter and the deflection of the meter was as shown in the opposite figure. What type is the transistor (npn or pnp)? Explain.

When an npn transistor was used in a common emitter circuit as an amplifier, the collector current was 99 mA and the product of the distribution ratio $(\alpha_e)$ and the amplification factor $(\beta_e)$ was 98.01. Calculate:
(1) the base current $(I_B)$.
(2) the emitter current $(I_E)$.

In a common emitter transistor circuit, prove that: $I_B = I_C (\frac{1}{\alpha_e} - 1)$

In the opposite transistor circuit, if the amplification factor is 30, calculate:
(1) the base current $(I_B)$.
(2) the distribution constant $(\alpha_e)$.

The opposite figure shows an npn transistor circuit working as a closed switch, with two identical lamps $P_1$ and $P_2$:
(1) What happens, with explanation, to the brightness of the two lamps when the slider is moved from point x towards point y?
(2) Draw the graph of the relation between the potential difference $(V_1)$ across lamp $P_1$ and the potential difference $(V_2)$ across lamp $P_2$

The opposite figure shows a transistor connected in series with a small lamp that works on a DC voltage:
(1) Complete the circuit diagram so that the lamp lights.
(2) What change would you make to the circuit in the previous case so that the lamp does not light?

In the opposite electronic circuit, a photocell (x) is connected to the base of an npn transistor, and the emitter and collector of the transistor are connected to an electric lamp (y). Explain why the lamp lights when daylight is gone.

Give a reason:
(1) There are defects in sound and picture in analog transmission.
(2) Digital electronics are preferred to analog electronics in electronic devices.

What is the scientific idea on which digital electronics are based?

Find the binary number equivalent to each of the following decimal numbers:
(1) 59
(2) 120

Find the decimal number equivalent to each of the following binary numbers:
(1) $(100110)_2$
(2) $(10011011)_2$

Find the decimal number for the quotient of the two binary numbers $\frac{(11110)_2}{(110)_2}$

Deduce the truth table of a circuit made of:
(1) a two-input AND followed by an inverter.
(2) a two-input OR followed by an inverter.

Complete the truth table of the following electronic circuits and convert the output to a decimal number:
Circuit (1)

Complete the truth table of the following electronic circuits and convert the output to a decimal number:
Circuit (2)

Complete the truth table of the following electronic circuits and convert the output to a decimal number:
Circuit (3)

Complete the truth table of the following electronic circuits and convert the output to a decimal number:
Circuit (4)

Complete the truth table of the following electronic circuits and convert the output to a decimal number:
Circuit (5)

Complete the truth table of the following electronic circuits and convert the output to a decimal number:
Circuit (6)

Write the truth table of the following logic circuits:

From the following truth table:
(1) Deduce the types of the gates X, Y, Z
(2) Complete the table.

From the following truth table, deduce the types of the gates X, Y, Z:

The truth table in front of you gives some input and output values of the gate circuit shown in the figure:
(1) Identify the type of gate X and gate Y
(2) Find the output Z in the table.

The electric circuit shown in the figure works like a group of logic gates, where the switches A and B are the inputs and the lighting of lamp C is the output:
(1) Complete the opposite truth table.
(2) Draw the logic gate circuit that satisfies the opposite truth table.

The opposite circuit is a transistor circuit of an inverter gate. If the output voltage $(V_{CE})$ is 0.8V when the base circuit resistance $(R_B)$ is 4000Ω, the collector circuit resistance $(R_C)$ is about ... (Trial exam / June 2021)

1. A $73.7 \times 10^{2} \Omega$
2. B $7370 \times 10^{2} \Omega$
3. C $7.37 \times 10^{2} \Omega$
4. D $0.737 \times 10^{2} \Omega$

The figure shows a transistor working as an amplifier. If the voltmeter reading is 4.8V and $R_C$ is 4.5kΩ, the values of the two constants $\alpha_E$ and $\beta_E$ respectively are ... (Trial exam / June 2021)

1. A 0.97 , 32.32
2. B 0.95 , 33.67
3. C 0.99 , 99
4. D 0.75 , 3

If the base current in an npn transistor is 2mA and $\alpha_E$ is 0.97, the collector current is ... (1st session 2021, Sample exam 2025)

1. A 1.97 mA
2. B 64.67 mA
3. C 10 mA
4. D 50.67 mA

When an npn transistor is used as a current amplifier, if the base current is 1mA and the current amplification ratio $(\beta_e)$ is 200, the collector current is ... (1st session 2021)

1. A 0.02 A
2. B 2 A
3. C 0.2 A
4. D 20 A

The opposite figure shows an npn transistor circuit whose amplification factor $\beta_e$ is 30. If $R_C$ is 50kΩ, the base current $(I_B)$ is ... (2nd session 2021)

1. A $3 \times 10^{-6}$
2. B $9.3 \times 10^{-5}$
3. C $8.7 \times 10^{-6}$
4. D $9 \times 10^{-5}$

In the opposite circuit the transistor is used as a switch. If the output voltage $(V_{CE})$ is 0.2V and the battery voltage in the collector circuit is 1.5V, the potential difference across the collector resistance $(R_C)$ is ... (2nd session 2021)

1. A 1.7 V
2. B 1.3 V
3. C 0.3 V
4. D 7.5 V

The figure shows an (npn) transistor used as an amplifier. The ratio $(\frac{\alpha_e}{\beta_e})$ = ... (1st session 2022)

1. A $2.7 \times 10^{-3}$
2. B $2.1 \times 10^{-2}$
3. C $1.1 \times 10^{-2}$
4. D $2.8 \times 10^{-3}$

If the distribution ratio $(\alpha_e)$ of a transistor is 0.99, the ratio $\frac{I_E}{I_B}$ = ... (2nd session 2022)

1. A 100
2. B 99
3. C 200
4. D 198

If the base current in an npn transistor is 6uA and $(\alpha_e = 0.95)$, the currents through the emitter and the collector respectively are ... (Trial exam 2023)

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

In a transistor circuit, if the emitter current is 120 times the base current, the value of the constant $(\alpha_e)$ ... (1st session 2023)

1. A 0.96
2. B 120
3. C 119
4. D 0.99

The circuit in the figure shows a transistor used as a switch. When $R_B$ is doubled, which choice correctly describes what happened to $V_{CC}$? (2nd session 2023)

1. A it stays constant
2. B it is halved
3. C it is doubled
4. D it equals zero

A transistor has a current amplification ratio $(\beta_e)$ of 150, so the value of the constant $(\alpha_e)$ is ... (2nd session 2023)

1. A 1.01
2. B 0.99
3. C 0.97
4. D 1.1

The figure shows an (npn) transistor circuit with amplification factor $(\beta_e = 99)$. The collector current $(I_C)$ and the output voltage $(V_{CE})$ respectively are ... (1st session 2024)

1. A 2.982 V , 0.06 uA
2. B 1.782 V , 16.5 uA
3. C 1.218 V , 594 uA
4. D 2.982 V , 16.5 uA

If the amplification factor is $(\beta_e = 93.6)$, the ratio $(\frac{I_E}{I_B})$ = ... (2nd session 2024)

1. A 93.6
2. B 95.6
3. C 94.6
4. D 92.6

An npn transistor can be considered equivalent to two diodes connected together. Which of the following figures is the correct equivalent of the npn transistor? (Sample exam 2025)

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

A transistor is connected as shown in the figure. Which of the following choices correctly describes the use of the transistor in this circuit? (Sample exam 2025)

1. A It amplifies both the electric power and the electric current
2. B It amplifies the electric power but not the electric current
3. C It amplifies the electric current but not the electric power
4. D It amplifies neither the electric power nor the electric current

In a transistor circuit, ($V_{CC} = 1.5V$) and the potential difference between the collector and the emitter is $(V_{CE} = 0.5V)$ (Sample exam 2025)
and the collector circuit resistance is $(R_C = 500 \Omega)$.
Calculate the collector current $(I_C)$.

A group of logic gates has an output voltage of (1) as in the figure. Which of the cases shown in the table gives this? (Trial exam / June 2021)

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

Which of the following logic circuits gives the input and output voltages shown in the opposite table? (1st session 2021)

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

A group of logic gates has an output voltage of (1) as in the figure. Which of the choices shown in the table for the two input voltages X, Y gives this? (2nd session 2021, 1st session 2022)

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

In which of the following logic circuits is the output voltage X high? (2nd session 2022)

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

In the logic gate circuit shown in the figure, which of the following choices makes the output (N) equal (0)? (Trial exam 2023)

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

Which of the following electric circuits represents the work of the group of logic gates shown in the opposite figure? (1st session 2023)

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

The figure shows an electric circuit where X, Y, Z are switches that are the inputs of a logic gate circuit, and the electric lamp is the output. Which of the groups shown does this circuit represent? (2nd session 2023)

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

The figure shows an electric circuit equivalent to a logic gate circuit. Which of the following logic gate circuits does this electric circuit work like? (1st session 2024)

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

The opposite figure shows several logic gates connected together. Which of the following choices gives a high output? (2nd session 2024)

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

The logic gate whose electric circuit has two switches connected in parallel is the .......... gate (Sample exam 2025)

1. A NOT
2. B AND
3. C OR
4. D NOT or AND

A group of logic gates is connected together as shown in the figure. Which of the following choices can be obtained from this group? (Sample exam 2025)

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

The figure shows part of a circuit with several logic gates, where the output is (Low) when the input is as shown. So (G) may be ... (Sample exam 2025)

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

The figure shows an npn transistor circuit. What is the effect of increasing the variable resistance $(R_B)$ on the collector current $(I_C)$ and the output voltage $(V_{CE})$? (1st session 2025)

1. A collector current: increases, output voltage: increases
2. B collector current: decreases, output voltage: increases
3. C collector current: does not change, output voltage: decreases
4. D collector current: decreases, output voltage: does not change

In the transistor circuit shown in the figure, the ammeter reads 2 mA, so the voltmeter reading equals .......... (2nd session 2025)

1. A 0.9 V
2. B 0.3 V
3. C 0.6 V
4. D 0.5 V

The figure shows a group of logic gates connected together. Which of the following input values makes the output (N) equal (zero)? (1st session 2025)

1. A X = 0, Y = 1, Z = 0
2. B X = 1, Y = 1, Z = 0
3. C X = 1, Y = 1, Z = 1
4. D X = 0, Y = 0, Z = 0

The figure shows a group of logic gates connected together. Which of the following electric circuits represents the work of this group of gates? (2nd session 2025)

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

The figure shows some logic gates connected to each other. The number of cases in which the output is (high) is .......... (Sample exam 2026)

1. A 0
2. B 1
3. C 2
4. D 3