# Multiple Choice Questions for Electronics Engineering Part 4

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Q.54 In a tunnel diode, electrons can tunnel through the P-N junction mainly because

impurity level is low

they have high energy

barrier potential is very low

depletion layer is extremely thin

Answer: 4

Q.55 Most of the transistors are NPN type and not PNP type because

NPN transistor gives large voltage gain

NPN transistors are more negative than PNP transistors

In NPN transistor, the current conduction is by free electrons which are less obiles than holes

We can have high conduction is NPN transistors

Answer: 4

Q.56 In a transistor

Emitter is heavily doped while the collector moderately doped

Collector base junction is forward biased

Emitter is made wider than collector

The input resistance is much larger than output resistance

Answer: 1

Q.57 If the instantaneous current in a ckt is given I=2 cos (t +) amperes, the r.m.s. value of t current is

2 amp

2 amp

2 2 amp

Zero amp

Answer: 2

Q.58 In an A.C. ckt, voltage and current are given V = 100 sin (100t) volts i = 100 sin (10t+) mA. The power dissipated in the ckt is

10

^{4}watts10 watts

2.5 watts

5 watts

Answer: 3

Q.59 A 0.05 H-F capacitor charges through a resistor and is discharged through a resistor 20K. The time constant of the circuit is

the same both during charging and discharging

larger during charging process

larger during discharging process

none

Answer: 2

Q.60 The basic element of radio communica^{1}” system which generates radio waves is

micro phone

transmitter

transmitting antenna

Loudspeaker

Answer: 2

Q.61 The input frequency of a bridge rectifier is 50 its output frequency will be

25 Hz

50 Hz

75 Hz

100 Hz

Answer: 4

Q.62 Which of the following voltage is used represent binary '1' in digital circuits.

0 V

15 V

+5 V

25 V

Answer: 3

Q.63 Hexadecimal number system is used as hand language for representing

decimal number

binary number

octal number

all the above

Answer: 2

Q.64 Logic state 0 in positive logic corresponds to

zero voltage

positive voltage

higher voltage level

lower voltage level

Q.65 The o/p of a 2 - input OR gate is 1 when its

both inputs are 1

both inputs are 0

either input is 1

either input is 0

Answer: 3

Q.66 TTL logic family is most popularly used industries because it

provides greater operating speed

has a good fan in & fan out

has easy interface with other digital circuitry

all the above

Answer: 2

Q.67 Transformer cores are laminated in order to

simplify its construction

minimise eddy current loss

reduce cost

reduce hysteresis loss

Answer: 2

Q.68 The external characteristic of a shunt generator can be obtained directly from its – characteristic

internal

open-circuit

load-saturation

performance

Answer: 2

Q.69 Load saturation characteristic of a d.c. generator gives relation between

V and I

_{a}E and I

_{a}E

_{0}and I_{f}V and I

_{f}

Answer: 4

Q.70 The biggest advantage of T-T connection over the V-V connection of 3-phase power transformation is that it provides.

a set of balanced voltages under load

a true 3-phase, 4-wire system

a higher ratio of utilization

more voltages

Answer: 3

Q.71 The biggest advantage of T-T connection over the V-V connection of 3-phase power transformation is that it provides.

a set of balanced voltages under load

a true 3-phase, 4-wire system

a higher ratio of utilization

more voltages

Answer: 2

Q.72 U.H.F. band covers the range of

0-300 KHz

3-30 MHz

300-3000 KHz

300 MHz - 3 GHz

Answer: 4

Q.73 The ripple factor of a bridge rectifier is

0.48

0.812

1.11

1.21

Answer: 1

Q.74 The high level language is/are

Machine language

BASIC

Assembly language

PASCAL

Answer: 2,4

Q.75 The high level language can be translated into machine language with the help of

Assembler

Stack pointer

Compiler

Multiplexer

Answer: 3

Q.76 In the emitter characteristic of UJT, the negative resistance portion.

lies in the cut-off region

continues up to peak point

lasts until the valley point is reached

does not exist

Answer: 3

Q.77 After firing as SCR, the gating pulse is removed. The current in the SCR will

remain the same

immediately fall to zero

rise up

None

Answer: 1

Q.78 When reverse bias is applied to a junction diode, it

Increases the potential barrier

Decreases the potential barrier

greatly increases the minority carrier current

greatly increases the majority carrier current

Answer: 1

Q.79 Transformer cores are laminated in order to

simplify its construction

minimise eddy current loss

reduce cost

reduce hysteresis loss

Answer: 2

Q.80 When a P – N junction is forward biased

Only electrons in N-region are injected into P-region

Only holes in P-region are injected into N-region

Majority carriers in each region are injected into the other region

Minority current is reduced to zero

Answer: 3