BASIC ELECTRONICS MCQs 1
Choose correct or the best alternative in the following: BASIC ELECTRONICS MCQs
Q.1 The breakdown mechanism in a lightly doped p-n junction under reverse biased condition is called
- (A) Avalanche breakdown.
- (B) Zener breakdown.
- (C) Breakdown by tunnelling.
- (D) High voltage breakdown.
Ans: A
Q.2 In a CE – connected transistor amplifier with voltage – gain A v, the capacitance Cbc is amplified by a factor
Q.3 For a large values of |VDS|, a FET – behaves as
- (A) Voltage controlled resistor.
- (B) Current controlled current source.
- (C) Voltage controlled current source.
- (D) Current controlled resistor.
Ans: C
Q.4 Removing bypass capacitor across the emitter-leg resistor in a CE amplifier causes
- (A) Increase in current gain.
- (B) Decrease in current gain.
- (C) Increase in voltage gain.
- (D) Decrease in voltage gain.
Ans: D
Q.5 For an op-amp having differential gain Av and common-mode gain Ac the CMRR is given by
Ans: B
Q.6 When a step-input is given to an op-amp integrator, the output will be
- (A) A ramp.
- (B) A sinusoidal wave.
- (C) A rectangular wave.
- (D) A triangular wave with dc bias.
Ans: A
Q.7 Hysteresis is desirable in Schmitt-trigger, because
- (A) Energy is to be stored/discharged in parasitic capacitances.
- (B) Effects of temperature would be compensated.
- (C) Devices in the circuit should be allowed time for saturation and desaturation.
- (D) It would prevent noise from causing false triggering.
Ans: C
Q.8 In a full-wave rectifier without filter, the ripple factor is
- (A) 0.482
- (B) 1.21
- (C) 1.79
- (D) 2.05
Ans: A
Q.9 A minterm of the Boolean-function, f(x, y, x) is
- (A) z y x + + ′
- (B) z y x ′
- (C) x z
- (D)(y +z) x
Ans: B
Q.10 The minimum number of flip-flops required to construct a mod-75 counter is
- (A) 5
- (B) 6
- (C) 7
- (D) 8
Ans: C
Q.11 Space charge region around a p-n junction
- (A) Does not contain mobile carriers
- (B) Contains both free electrons and holes
- (C) Contains one type of mobile carriers depending on the level of doping of the p or n regions
- (D) Contains electrons only as free carriers
Ans: A
Q.12 The important characteristic of emitter-follower is
- (A) High input impedance and high output impedance
- (B) High input impedance and low output impedance
- (C) Low input impedance and low output impedance
- (D) Low input impedance and high output impedance
Ans: B
Q.13 In a JFET, at pinch-off voltage applied on the gate
- (A) The drain current becomes almost zero
- (B) The drain current begins to decrease
- (C) The drain current is almost at saturation value.
- (D) The drain-to-source voltage is close to zero volts.
Ans: C
Q.14 When an amplifier is provided with current series feedback, its
- (A) Input impedance increases and output impedance decreases
- (B) Input and output impedances both decrease
- (C) Input impedance decreases and output impedance increases
- (D) Input and output impedances both increase
Ans: D
Q.15 The frequency of oscillation of a tunnel-collector oscillator having L= 30µH and C = 300pf is nearby
- (A) 267 kHz
- (B) 1677 kHz
- (C) 1.68 kHz
- (D) 2.67 MHz
Ans: B
Q.16 The open-loop gain of an op-amp available in the market may be around.
- (A) 10–1
- (B) 10
- (C) 105
- (D) 102
Ans: C
Q.17 The control terminal (pin5) of 555 timer IC is normally connected to ground through a capacitor (~ 0.01µF). This is to
- (A) Protect the IC from inadvertent application of high voltage
- (B) Prevent false triggering by noise coupled onto the pin
- (C) Convert the trigger input to sharp pulse by differentiation
- (D) Suppress any negative triggering pulse
Ans: B
Q.18 The value of ripple factor of a half-wave rectifier without filter is approximately
- (A) 1.2
- (B) 0.2
- (C) 2.2
- (D) 2.0
Ans: A
Q.19 The three variable Boolean expression xy + xyz + x y + x y z
Ans: C 
Q.20 The fan-out of a MOS-logic gate is higher than that of TTL gates because of its
- (A) Low input impedance
- (B) High output impedance
- (C) Low output impedance
- (D) High input impedance
Ans: D
(BASIC ELECTRONICS MCQs)