Electronic Design Quiz # 1

A Colpitt’s oscillator uses _____.

a tapped inductor

a tapped capacitor

no tapped inductor or capacitor

both a tapped inductor and a tapped capacitor

A Wien-bridge oscillator is basically a _____.

pulse generator

sine-wave generator

square-wave generator

triangular wave generator

A voltage V=300cos100t is applied to a half wave rectifier with RL =5KΩ. The rectifier may be represented by an ideal diode in series with a resistance of 1KΩ. What would be the ripple factor in this case?

0

100%

110.21%

121.13%

A bridge rectifier circuit has secondary voltage of 12Vr.m.s. Assume secondary resistance and diode forward resistance to be negligible. The load resistance is 100Ω. What would be the peak load current?

0.169 Amp

0.108 Amp

0.118 Amp

11.8 Amp

A half wave rectifier supplies power to 1000Ω load from a 110V (r.m.s) source of supply. If the forward resistance of the diode is 20Ω. What would be the efficiency of the rectifier?

50%

25.73%

39.73%

30.11%

After triggering an SCR , the gate pulse is removed. the current in the SCR will _____.

remain the same

immediately fall to zero

rise-up

rise a little and fall to zero

A feedback amplifier has an internal gain = 40dB and a feedback factor = 0.05, if the input impedance of this circuit is 12KΩ. What would have been the input impedance of the amplifier if the feedback had not been present?

1KΩ

2KΩ

3KΩ

4KΩ

An amplifier has a gain of 10 without feedback. To make it oscillate, ß must be _____.

0.2

0.1

0.5

0.8

For designing a Push-Pull amplifier, the type of transistors should be _____.

one should be p-n-p and the other should be n-p-n

Both should be either p-n-p or n-p-n

both should be n-p-n only

All of the above

A crystal oscillator provides very stable frequency because of _____.

the high stability of the crystal

the rigid crystal structure

the low XL/R ratio of the crystal

the high Q of the crystal

A transistor is a semiconductor switch which is _____.

unilateral and astable

bilateral and astable

unilateral and bistable

bilateral and bistable

An Emitter follower is used for _____.

high current gain

high voltage gain

impedance matching

high power gain

An amplifier has a bandwidth of 200KHz and a voltage gain of 100. What will be the new bandwidth if 5% negative feedback is introduced?

1000KHz

1200KHz

1600KHz

2000KHz

A differentiator converts a linear ramp into a _____.

triangular wave

square wave

sinusoidal wave

constant D.C signal

Most SCRs can be turned-off by voltage reversal during the negative half-cycle of the A.C supply for _____.

all frequencies

frequencies up to 300Hz

frequencies up to 30KHz

frequencies up to 300KHz

One of the ways to destroy a diode is _____.

to exceed the current limit in forward direction

to apply a small voltage in the reverse direction

to dip it in water

to drop on the floor

For class-AB power amplifier, the output current flows _____.

for more than 90° but less than 180°

for more than 270° but less than 360°

for more than 180° but less than 360°

for more than 45° but less than 90°

What would be the output of a voltage follower if it has an input of 0.3Vpp?

0.6 Vpp

0.3 Vpp

v3 Vpp

v2 Vpp

The dV/dt capability of the thyristor is _____ that of the triac.

lower than

higher than

equal to

None of the above

In a class-B power amplifier, the output signal is obtained only _____.

for one half cycle period of the input A.C signal

for full cycle period of the input A.C signal

for quarter cycle period of the input A.C signal

Which of the following does not cause permanent damage to an SCR?

High current

High rate of the rise of the current

High temperature rise

High rate of the rise of the voltage

Which semiconductor power device out of the following is not a current triggered device?

Thyristor

GTO

Triac

MOSFET

An emitter follower is found to have a voltage gain of 0.99. What would be the value of ß for its transistors?

100

99

33

6

Both positive and negative feedbacks are employed in _____.

a Hartley Oscillator

a Colpitt’s Oscillator

a Tuned – Collector Oscillator

a Wien Bridge Oscillator

Which one of the following amplifiers has the highest efficiency?

Class-A

Class-B

Class-C

Class-AB

How much power is dissipated in the individual transistor of a Class-B push-pull amplifier if Vcc=20V and R1=4Ω (primary resistance)

9W

12W

10.13W

20.26W

In a negative feedback circuit , the feedback factor is always between _____.

0 and 1

1 and 2

2 and 3

3 and 4

The transistor equivalent of the thyratron tube is _____.

SCR

UJT

Diac

Triac

The loop gain of the oscillator to start with is _____.

slightly more than one

more than 100

less than one

None of the above

The Hall Effect voltage in intrinsic silicon _____.

is positive

is zero

is negative

changes the sign on the application of the magnetic field