Explore topic-wise MCQs in Electronics & Communication Engineering.

This section includes 1136 Mcqs, each offering curated multiple-choice questions to sharpen your Electronics & Communication Engineering knowledge and support exam preparation. Choose a topic below to get started.

51.

A transistor with a = 0.9 and ICBO = 10 μA is biased so that IBQ = 90 μA. Then IEQ will be

A. 5.15 mA
B. 5.2 mA
C. 5 mA
D. 990 mA
Answer» E.
Discussion
52.

The transistor of following figure in Si diode with a base current of 40 μA and ICBO = 0, if VBB = 6V, RE = 2 kΩ and β = 90, IBQ = 20 μA then IEQ =

A. 1800 μA
B. 180 μA
C. 2000 μA
D. 3000 μA
Answer» B. 180 μA
Discussion
53.

A transistor with a = 0.9 and ICBO = 10 μA is biased so that IBQ = 90 μA. Then ICQ will be

A. 910 mA
B. 5 mA
C. 5.25 mA
D. 4.95 mA
Answer» B. 5 mA
Discussion
54.

For a BJT if β = 50, ICEO = 3 μA and IC = 1.2 mA then IE

A. 1 mA
B. 1.2 mA
C. 1.3 mA
D. 1.4 mA
Answer» C. 1.3 mA
Discussion
55.

In the following figure C = 0.02 μF, and Vth is known to be of frequency ω = 107 rad/sec and rd = 2.5 Ω and ZTh = RTh = 10 Ω Then phase angle between id and Vd

A. 26.5°
B. 25°
C. 30°
D. 0°
Answer» B. 25°
Discussion
56.

For a BJT if β = 50, ICEO = 3 μA and IC = 1.2 mA then IB

A. 24 μA
B. 23 μA
C. 20 μA
D. 10 μA
Answer» B. 23 μA
Discussion
57.

A Ge diode operated at a junction temperature of 27°C. For a forward current of 10 mA, VD is found to be 0.3 V. If VD = 0.4 V then forward current will be

A. 400 mA
B. 475 mA
C. 477 mA
D. 480 mA
Answer» D. 480 mA
Discussion
58.

Values of VT at 20°C for an ideal P-N diode

A. 25.27 mV
B. 30.3 mV
C. 23 mV
D. 50 mV
Answer» B. 30.3 mV
Discussion
59.

Percentage increase in the reverse saturation current of a diode if the temperature is increased from 25°C to 50°C

A. 50%
B. 500%
C. 565.7%
D. 575.6%
Answer» D. 575.6%
Discussion
60.

Voltage VL in the circuit when Vs < 0 where D is an ideal diode. (Take R1 = Rs = RL = 1 &ohm;)

A. 0
B. 1
C. 1.5
D. cannot find
Answer» B. 1
Discussion
61.

A distorted sinusoidal has the amplitudes A1, A2, A3 ... of the fundamental, second, harmonic third harmonic, ... respectively. The total harmonic distortion is

A. [A].
B. [B].
C. [C].
D. [D].
Answer» C. [C].
Discussion
62.

The common emitter short circuit current gain β of a transistor

A. is a monotonically increasing function of the collector current Ic
B. is a monotonically decreasing function of Ic
C. increasing with Ic, for low Ic, reaches a maximum and then decreases with further increase in Ic
D. is not a function of Ic
Answer» D. is not a function of Ic
Discussion
63.

An npn transistor has a Beta cutoff frequency fβ of 1 MHz, and a common emitter short circuit low frequency current gain β0 of 200. It unity gain frequency fT and the alpha cut off frequency fa2 respectively are

A. 200 MHz, 201 MHz
B. 200 MHz, 199 MHz
C. 199 MHz, 200 MHz
D. 201 MHz, 200 MHz
Answer» B. 200 MHz, 199 MHz
Discussion
64.

In the circuit of the given figure, assume that the diodes are ideal and the meter is an average indicating ammeter, the ammeter will read

A. 0.42 A
B. 0.4 A
C. [C].
D. 0.4/p mA
Answer» E.
Discussion
65.

For the circuit shown in the figure, the capacitor C is initially uncharged. At t = 0, the switch S is closed. The voltage Vc across the capacitor at t = 1 millisecond is (In the figure shown above, the op-amp is supplied with ± 15 V and the ground has been shown by the symbol)

A. 0 V
B. 6.3 V
C. 9.45 volts
D. 10 volts
Answer» E.
Discussion
66.

A silicon PN junction diode under reverse bias has depletion region of width 10 μm. The relative permittivity of silicon, εr = 11.7 and the permittivity of free space ε0 = 8.85 x 10-12 F/m. The depletion capacitance of the diode per square meter is

A. 100 μF
B. 10 μF
C. 1 μF
D. 20 μF
Answer» C. 1 μF
Discussion
67.

In the op-amp circuit given in the figure, the load current iL is

A. [A].
B. [B].
C. [C].
D. [D].
Answer» B. [B].
Discussion
68.

Assuming VCE sat = 0.2 V and β = 50, the minimum base current (IB) required to drive the transistor in the given figure to saturation is

A. 56 μA
B. 140 μA
C. 60 μA
D. 3 μA
Answer» B. 140 μA
Discussion
69.

In the figure, assume the op-amp is to be ideal. The output Vo if the circuit is

A. 10 cos (100t)
B. [B].
C. [C].
D. [D].
Answer» B. [B].
Discussion
70.

Volt equivalent temperature in a PN Junction diode is

A. [A].
B. [B].
C. [C].
D. 11600 T
Answer» B. [B].
Discussion
71.

An inverting amplifier has R1 = 10 k&ohm;, and Rf = 150 k&ohm; then the O/P voltage, if input voltage Vi = 1 volt.

A. -15 V
B. -10 V
C. 15 V
D. -14 V
Answer» B. -10 V
Discussion
72.

An R-C coupled amplifier has mid-frequency gain of 200 and a frequency response from 100 Hz to 20 kHz. A negative feedback network with β = 0.2 is incorporated into the amplifier circuit, the Bandwidth will be

A. 50 kHz
B. 20 kHz
C. 100 kHz
D. infinite
Answer» D. infinite
Discussion
73.

In a negative feedback amplifier A = 100, β = 0.04 and Vs = 50 mV, then feedback will be

A. 4
B. 8
C. 10
D. 2
Answer» B. 8
Discussion
74.

A full wave rectifier supplies a load of 1 k&ohm;. The a.c. Voltage applied to the diodes is 220 - 0 - 220 Volts rms. If diode resistance is neglected, then Average d.c. Voltage

A. 220 V
B. 200 V
C. 198 V
D. 0 volts
Answer» D. 0 volts
Discussion
75.

In a half wave rectifier, Vrms is

A. [A].
B. [B].
C. [C].
D. None of these
Answer» B. [B].
Discussion
76.

For a BJT, β and a are related as

A. [A].
B. [B].
C. [C].
D. [D].
Answer» E.
Discussion
77.

Calculate the conductivity of pure silicon at room temperature when the concentration of carriers is 1.6 x 1010 per cm3. Take μe = 1500 cm2/V-sec, μh = 500 cm2/V-sec at room temperature,

A. 5.12 x 10-16
B. 5 x 10+16
C. 1016
D. 5 x 1020
Answer» B. 5 x 10+16
Discussion
78.

The turn ratio of a transformer is 20:1, if a load of 10&ohm; is connected across the secondary, what will be the effective resistance seen looking into the Primary?

A. 2 k&ohm;
B. 4 k&ohm;
C. 8 k&ohm;
D. 32 k&ohm;
Answer» C. 8 k&ohm;
Discussion
79.

Calculate the O/P voltage of a non-inverting constant gain multiplier with R1 = 100 k&ohm;, Rf= 600 k&ohm;, V1 = 2 volt, then O/P voltage Vo of non inverting op-amp is given by

A. 16 V
B. 14 V
C. 20 V
D. 15 V
Answer» C. 20 V
Discussion
80.

Oscillation frequency in Wein bridge oscillator is

A. [A].
B. [B].
C. f = 2p CR
D. [D].
Answer» B. [B].
Discussion
81.

The RC network of wein bridge oscillator consists of resistors and capacitors of values R = 220 k&ohm; and C = 250 PF Determine the frequency of oscillation

A. 2.98 kHz
B. 3 kHz
C. 2 kHz
D. 10 kHz
Answer» B. 3 kHz
Discussion
82.

Oscillation frequency in colpitt's oscillator is

A. [A].
B. [B].
C. [C].
D. none of these
Answer» B. [B].
Discussion
83.

The current through R1 is(If β = 99, VBE = 0.74 V)

A. 0.1 mA
B. 0.35 mA
C. 0.2 mA
D. none
Answer» B. 0.35 mA
Discussion
84.

Gain of the amplifier is 'A'. Then the I/P impedance and O/P impedance of the closed loop amplifier shown below would be

A. [A].
B. [B].
C. [C].
D. [D].
Answer» C. [C].
Discussion
85.

In a circuit of figure, Vs = 10 cos(ωt) power drawn by the 2&ohm; resistor is 4 watts. The power factor is

A. 0.3
B. 0.4
C. 0.6
D. none
Answer» D. none
Discussion
86.

If an amplifier with gain of - 100 and feedback of β = - 0.1 has a gain change of 20% due to temperature the change in gain of the feedback amplifier will be

A. 0.02%
B. 2%
C. 0.1%
D. 0.01%
Answer» C. 0.1%
Discussion
87.

In the circuit shown in figure, RC = 10k, RE = 150&ohm;, β = 100, I = 1 mA. The value of , will be

A. 50
B. 100
C. 192
D. 400
Answer» D. 400
Discussion
88.

A voltage gain of a CE amplifier connected in collector to base configuration is 50. Collector to base resistor RF = 1 k&ohm;, RC = 4&ohm;, the O/P resistance R0 =?

A. 800 &ohm;
B. 813 &ohm;
C. 817 &ohm;
D. 819 &ohm;
Answer» C. 817 &ohm;
Discussion
89.

In a closed loop non-inverting amplifier, constructed using single break-frequency op-amp, bandwidth with feedback can be written as. (f0 - break frequency, β - gain of the feedback circuit, A - open loop voltage gain, Af - closed loop voltage gain)

A. [A].
B. [B].
C. [C].
D. [D].
Answer» B. [B].
Discussion
90.

Regulation of the DC power supply of 12 V, 100 mA is the effective resistance of power supply is 20 &ohm;

A. 22%
B. 131%
C. 30%
D. 20%
Answer» E.
Discussion
91.

For the amplifier in figure, β = 800. The mid-band voltage gain V0/Vi is

A. 0
B. < 1
C. ≈ 1
D. 800
Answer» D. 800
Discussion
92.

For transistor 2 N 338 the manufacturer specifies Pmax = 100 mW at 250°C free air temperature and maximum junction temperature of 125°C. Its thermal resistance is

A. 10° C/W
B. 100° C/W
C. 1000° C/W
D. 5000° C/W
Answer» D. 5000° C/W
Discussion
93.

An amplifier has open loop gain of 100, input impedance 1 k&ohm; and output impedance 100 &ohm;. If negative feedback with β = 0.99 is used, the new input and output impedances are

A. 10 &ohm; and 1 &ohm;
B. 10 &ohm; and 10 k&ohm;
C. 100 k&ohm; and 1 &ohm;
D. 100 k&ohm; and 10 &ohm;
Answer» D. 100 k&ohm; and 10 &ohm;
Discussion
94.

A class C amplifier has input frequency of 200 kHz. If width of collector pulses is 0.1 μs, duty cycle is

A. 1%
B. 2%
C. 10%
D. 20%
Answer» C. 10%
Discussion
95.

The ripple factor of a power supply is

A. [A].
B. [B].
C. [C].
D. [D].
Answer» C. [C].
Discussion
96.

For the amplifier circuit of figure, the h parameters of transistor are hib = 25 &ohm;, hfb = 0.999, hob = 10-6 &ohm;. The voltage gain is

A. 0.999
B. 1.98
C. 20
D. 400
Answer» E.
Discussion
97.

In an amplifier with a gain of - 1000 and feedback factor β = - 0.1, the change in gain is 20% due to temperature. The change in gain for feedback amplifier will be

A. 10%
B. 5%
C. 0.2%
D. 0.01%
Answer» D. 0.01%
Discussion
98.

In a transistor IE = 10 mA, ICO = 0.5 μA and a = 0.995. Then ICEO =

A. 100 μA
B. 25 μA
C. 10.1 mA
D. 10.5 mA
Answer» B. 25 μA
Discussion
99.

For the circuit of figure the critical frequency is

A. [A].
B. [B].
C. [C].
D. [D].
Answer» C. [C].
Discussion
100.

The critical frequency of the circuit of figure is

A. [A].
B. [B].
C. [C].
D. [D].
Answer» C. [C].
Discussion