Electronics and Experimental Methods (CSIR Physical Sciences): Questions 17 - 19 of 44

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Question number: 17

» Electronics and Experimental Methods » Semiconductor Devices » Diodes

Appeared in Year: 2013

MCQ▾

Question

Two identical Zener diodes are placed back to back in series and are connected to a variable DC power supply. The best representation of the I – V characteristics of the circuit is – (December)

Choices

Choice (4) Response

a.

I – V characteristics: Choice A

I – v Characteristics: Choice A

Figure shows I – V characteristic of circuit consists of two identical Zener diodes.

b.

I – V characteristics: Choice B

I – v Characteristics: Choice B

Figure shows I – V characteristic of circuit consists of two identical Zener diodes.

c.

I – V characteristics: Choice C

I – v Characteristics: Choice C

Figure shows I – V characteristic of circuit consists of two identical Zener diodes.

d.

I – V characteristics: Choice D

I – v Characteristics: Choice D

Figure shows I – V characteristic of circuit consists of two identical Zener diodes.

Question number: 18

» Electronics and Experimental Methods » Semiconductor Devices » Junctions

Appeared in Year: 2014

MCQ▾

Question

A junction is made between a metal of work function WM and a doped semiconductor of work function WS with WM>WS . If the electric field at the interface has to be increased by a factor of 3, then the dopant concentration in the semiconductor would have to be – (December)

Choices

Choice (4) Response

a.

Decreased by a factor of 3

b.

Decreased by a factor of 3

c.

Increased by a factor of 3

d.

Increased by a factor of 9

Question number: 19

» Electronics and Experimental Methods » Opto-Electronic Devices » LEDs

Appeared in Year: 2012

MCQ▾

Question

An LED operates at 1.5 V and 5 mA in forward bias. Assuming an 80 % external efficiency of the LED, how many photons are emitted per second? (June)

Choices

Choice (4) Response

a.

1.5×1016

b.

2.5×1016

c.

0.8×1016

d.

5.0×1016

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