Most Important Interview / VIVA Questions For Electronics & Communication Engineering
1.The impedance curve of an R-L-C network cuts the frequency axis only when the frequency is such that
(a) XL=XC
(b) XL=XC=0
(c) R=0 and XL=XC
(d) none of these
Ans: c
2.In a semiconductor diode, P-side is grounded and N-side is applied a potential of -5V through a resistance of 100 ohms. the diode shall
(a) conduct fully
(b) not conduct
(c) conduct partially
(d) none of these
Ans: a
3. the junction diode’s capacitance that is made use of in varactors is known as
(a) transition capacitance
(b) diffusion capacitance
(c) space charge capacitance
(d) inter-electrode capacitance.
Ans: a
4. when current through a zener diode increases by a factor of 2, voltage across its terminals
(a) is halved
(b) is doubled too
(c) is practically unchanged
(d) none of these
Ans: c
5. SCRs are connected in series to enchance
(a) their overall dv/dt rating
(b) their voltage ratings
(c) their current handling capabilities
(d) none of these
Ans: b
6. the condition that decides the oscillator’s out put frequency is :
(a) loop gain should at least be unity
(b) loop phase-shift should be zero or integral multiple of 2p radians
(c) loop gain should be precisely unity
(d) loop phase-shift should be precisely zero radian.
Ans: b
7. most popular oscillator configuration for audio applications is :
(a) Hartley oscillator
(b) colpitt’s oscillator
(c) wein-bridge oscillator
(d) R-C phase shift oscillator.
Ans: c
8. pick the odd-one out :
(a) Hartley oscillator
(b) collpitt oscillator
(c) clap oscillator
(d) wein bridge oscillator
Ans: d
9.the output voltage at no load in an unregulated power supply is the same as its output voltage at rated load current. its internal resistance is therefore
(a) extremely small
(b) zero
(c) infinite
(d) extremely large.
Ans: b
10. mark the rectifier circuit that produces the least ripple
(a) single rectifier,half wave, single phase
(b) four rectifiers,full wave,single phase
(c) two rectifiers,full wave,single phase
(d) six rectifiers,full wave,three phase.
Ans: d
11. indicate the false statement
(a) closed loop gain is always less than the open loop gain.
(b) input impedance is always greater than the out put impedance
(c) the open loop gain falls to zero decibel at a frequency equal to unity gain crossover frequency
(d) closed loop bandwidth is always greater than the open loop bandwidth
Ans: d
12. one of the following statements in reference to a unity gain noninverting buffer using an opamp is in correct. identify this statement
(a) it has extremely high input impedance,much higher than even its open loop input impedance
(b) its input impedance is very high almost approaching its open loop input impedance magnitude
(c) the voltage gain is unity.
(d) the inputis applied to the non-inverting input
(e) the feed back magnitude is 100 percent.
Ans: b
13.the SLEW RATE specification of an opamp is usually measured in
(a) microvolts per second
(b) volts per microsecond
(c) decibels
(d) volts per microvolt
Ans: b
14. a given opamp has an open loop gain of 110dB and a CMRR rating of 106dB. what should be the open loop common mode gain of this op-amp?
(a) it cannot be determined from the given data
(b) 4dB
(c) 216 dB
(d) 110Db
Ans: b
15. in a 555 astable multivibrator operating from Vcc of 15V, the output wave from duty cycle is 0.4 (duty cycle = ON-time/total time period.) the circuit is slightly modified with the capacitor now charging from a voltage of 30V rather than Vcc. the duty cycle of the output waveform in the modified circuit will
(a) remain unchanged
(b) become about 0.6
(c) be approximately 0.2
(d) none of these
Ans: c
16. the pulse width in a 555 monostable multivibrator is given by
(a)t = 0.69 RC
(b)t = 1.1 RC
(c)t = RC
(d) none of these
Ans: b
17. in the astable mode of operation of IC 555, the timing capacitor always charges between
(a) 0 and 1/3 Vcc
(b) 1/3 Vcc and 2/3Vcc
(c) 0 and 2/3 Vcc
(d) 0 and Vcc
Ans: b
18.when a PLL is being used as an FM demodulator,the demodulated signal appears at
(a) the output of phase comparator
(b) the output of low pass filter
(c) the VCO output
(d) none of these.
Ans: b
19.”A NOR gate is equivalent to a bubbled AND gate”. this statement is an outcome of
(a) demorgan’s theorems
(b) involution law
(c) absorption law
(d) idempotent law
Ans: a
20.for one of the following conditions, clocked j-k flip flop can be used as DIVIDE BY 2 circuit where the pulse train to be divided is applied at clock input.
(a) J=1, K=1 and the flip flop should have active HIGH inputs
(b) J=1, K=1 and the flip flop should have active LOW inputs
(c) J=0, K=0 and the flip flop should have active high inputs
(d) J=1, K=1 and the flip flop should be a negative edge triggered one.
Ans: a
1.The impedance curve of an R-L-C network cuts the frequency axis only when the frequency is such that
(a) XL=XC
(b) XL=XC=0
(c) R=0 and XL=XC
(d) none of these
Ans: c
2.In a semiconductor diode, P-side is grounded and N-side is applied a potential of -5V through a resistance of 100 ohms. the diode shall
(a) conduct fully
(b) not conduct
(c) conduct partially
(d) none of these
Ans: a
3. the junction diode’s capacitance that is made use of in varactors is known as
(a) transition capacitance
(b) diffusion capacitance
(c) space charge capacitance
(d) inter-electrode capacitance.
Ans: a
4. when current through a zener diode increases by a factor of 2, voltage across its terminals
(a) is halved
(b) is doubled too
(c) is practically unchanged
(d) none of these
Ans: c
5. SCRs are connected in series to enchance
(a) their overall dv/dt rating
(b) their voltage ratings
(c) their current handling capabilities
(d) none of these
Ans: b
6. the condition that decides the oscillator’s out put frequency is :
(a) loop gain should at least be unity
(b) loop phase-shift should be zero or integral multiple of 2p radians
(c) loop gain should be precisely unity
(d) loop phase-shift should be precisely zero radian.
Ans: b
7. most popular oscillator configuration for audio applications is :
(a) Hartley oscillator
(b) colpitt’s oscillator
(c) wein-bridge oscillator
(d) R-C phase shift oscillator.
Ans: c
8. pick the odd-one out :
(a) Hartley oscillator
(b) collpitt oscillator
(c) clap oscillator
(d) wein bridge oscillator
Ans: d
9.the output voltage at no load in an unregulated power supply is the same as its output voltage at rated load current. its internal resistance is therefore
(a) extremely small
(b) zero
(c) infinite
(d) extremely large.
Ans: b
10. mark the rectifier circuit that produces the least ripple
(a) single rectifier,half wave, single phase
(b) four rectifiers,full wave,single phase
(c) two rectifiers,full wave,single phase
(d) six rectifiers,full wave,three phase.
Ans: d
11. indicate the false statement
(a) closed loop gain is always less than the open loop gain.
(b) input impedance is always greater than the out put impedance
(c) the open loop gain falls to zero decibel at a frequency equal to unity gain crossover frequency
(d) closed loop bandwidth is always greater than the open loop bandwidth
Ans: d
12. one of the following statements in reference to a unity gain noninverting buffer using an opamp is in correct. identify this statement
(a) it has extremely high input impedance,much higher than even its open loop input impedance
(b) its input impedance is very high almost approaching its open loop input impedance magnitude
(c) the voltage gain is unity.
(d) the inputis applied to the non-inverting input
(e) the feed back magnitude is 100 percent.
Ans: b
13.the SLEW RATE specification of an opamp is usually measured in
(a) microvolts per second
(b) volts per microsecond
(c) decibels
(d) volts per microvolt
Ans: b
14. a given opamp has an open loop gain of 110dB and a CMRR rating of 106dB. what should be the open loop common mode gain of this op-amp?
(a) it cannot be determined from the given data
(b) 4dB
(c) 216 dB
(d) 110Db
Ans: b
15. in a 555 astable multivibrator operating from Vcc of 15V, the output wave from duty cycle is 0.4 (duty cycle = ON-time/total time period.) the circuit is slightly modified with the capacitor now charging from a voltage of 30V rather than Vcc. the duty cycle of the output waveform in the modified circuit will
(a) remain unchanged
(b) become about 0.6
(c) be approximately 0.2
(d) none of these
Ans: c
16. the pulse width in a 555 monostable multivibrator is given by
(a)t = 0.69 RC
(b)t = 1.1 RC
(c)t = RC
(d) none of these
Ans: b
17. in the astable mode of operation of IC 555, the timing capacitor always charges between
(a) 0 and 1/3 Vcc
(b) 1/3 Vcc and 2/3Vcc
(c) 0 and 2/3 Vcc
(d) 0 and Vcc
Ans: b
18.when a PLL is being used as an FM demodulator,the demodulated signal appears at
(a) the output of phase comparator
(b) the output of low pass filter
(c) the VCO output
(d) none of these.
Ans: b
19.”A NOR gate is equivalent to a bubbled AND gate”. this statement is an outcome of
(a) demorgan’s theorems
(b) involution law
(c) absorption law
(d) idempotent law
Ans: a
20.for one of the following conditions, clocked j-k flip flop can be used as DIVIDE BY 2 circuit where the pulse train to be divided is applied at clock input.
(a) J=1, K=1 and the flip flop should have active HIGH inputs
(b) J=1, K=1 and the flip flop should have active LOW inputs
(c) J=0, K=0 and the flip flop should have active high inputs
(d) J=1, K=1 and the flip flop should be a negative edge triggered one.
Ans: a
No comments:
Post a Comment