Electronics and Communication Engineering - Electronic Devices and Circuits

1. 

Which of these has 3 layers?

A. PIN diode
B. Zener diode
C. Schottky diode
D. Photo diode

Answer: Option A

Explanation:

p layer, i layer and n layer.


2. 

As per Einstein's equation, the velocity of emitted electron in photoelectric emission is given by the equation

A. mv2 = hf - Uw
B. mv2hf - Uw
C. mv2 = hf + Uw
D. mv2hf + Uw

Answer: Option B

Explanation:

Some electrons have less energy than Fermi level E and, therefore, more energy than Uw to escape.

Therefore, this equation has inequality sign.


3. 

For an P-channel enhancement type MOSFET determine the drain current if K = 0.278 x 10-3A/V2, VGS = -4V, VT = -2V, Voltage equivalent at 27°C = 26 mV.

A. 10 mA
B. 1.11 mA
C. 0.751 mA
D. 46.98 mA

Answer: Option B

Explanation:

Drain current Id  = k (|Vgs| - |VT|)2

= 0.278 x 10-3(4 - 2)2

= 1.11 mA.


4. 

The skin depth of copper is found to be 66 mm at 1 MHz at a certain temperature. At the same temperature and at 2 MHz, the skin depth would be approximately

A. 47 μm
B. 33 μm
C. 92 μm
D. 1.22 μm

Answer: Option A

Explanation:

Skin depth =


5. 

When p-n junction is reverse biased the holes in p material move towards the junction and electrons in n material move away from the junction.

A. True
B. False

Answer: Option B

Explanation:

Both holes and electrons move away from junction.


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