# 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}watts - 10 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