ISCET Semiconductor Devices 2

Question 1

What is the primary function of the depletion region in a reverse-biased PN junction?

Accepted Answer

To act as an insulating barrier that blocks majority carrier flow

Answer

To increase forward current

Answer

To reduce junction capacitance to zero

Answer

To enhance minority carrier recombination

Question 2

A Zener diode is operating in reverse breakdown at 6.2 V with 20 mA flowing through it. What is the power dissipated?

Accepted Answer

0.124 W

Answer

0.31 W

Answer

124 W

Answer

3.1 W

Question 3

Which BJT configuration provides the highest voltage gain but has a current gain less than 1?

Accepted Answer

Common base

Answer

Common emitter

Answer

Common collector

Answer

Darlington pair

Question 4

In an N-channel JFET, pinch-off voltage (Vp) is the gate-to-source voltage at which:

Accepted Answer

The channel is fully depleted and drain current drops to nearly zero

Answer

Drain current reaches its maximum value

Answer

The device enters saturation

Answer

Gate current begins to flow

Question 5

Which parameter describes the ratio of the change in collector current to the change in base current in a BJT?

Accepted Answer

Beta (β)

Answer

Alpha (α)

Answer

Gamma (γ)

Answer

Transconductance (gm)

Question 6

A silicon diode has a forward voltage drop of approximately 0.7 V. If a germanium diode is used instead, the forward voltage drop would be approximately:

Accepted Answer

0.3 V

Answer

1.4 V

Answer

0.7 V

Answer

0.1 V

Question 7

What is the effect of increasing temperature on the reverse saturation current (IS) of a PN junction diode?

Accepted Answer

IS increases, roughly doubling for every 10°C rise

Answer

IS decreases exponentially

Answer

IS remains constant

Answer

IS becomes negative