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Electronics and Communication Engineering - Electromagnetic Field Theory

Exercise : Electromagnetic Field Theory - Section 4
36.
As temperature increases the forbidden gap in silicon increases.
True
False
Answer: Option
Explanation:

With increase in temperature, the forbidden gap decreases.

37.

Assertion (A): Germanium is more commonly used than silicon.

Reason (R): Forbidden gap in germanium is less than that in silicon.

Both A and R are true and R is correct explanation of A
Both A and R are true but R is not a correct explanation of A
A is true but R is false
A is false but R is true
Answer: Option
Explanation:

A is wrong because germanium is rarely used.

38.
Which of the following devices has substrate?
JFET
Depletion Type MOSFET
Enhancement type MOSFET
Both (b) and (c)
Answer: Option
Explanation:

All MOSFETs have substrate.

39.

Assertion (A): The amount of photoelectric emission depends on the intensity of incident light.

Reason (R): Photo electric emission can occur only if frequency of incident light is less than threshold frequency.

Both A and R are true and R is correct explanation of A
Both A and R are true but R is not a correct explanation of A
A is true but R is false
A is false but R is true
Answer: Option
Explanation:

Photo electric emission occurs only if frequency is higher than threshold frequency thus R is wrong.

40.
In degenerate p type semiconductor material, the Fermi level,
is in the valence band
is in conduction band
is at the centre in between valence and conduction bands
is very near conduction band
Answer: Option
Explanation:

This is due to heavy doping.

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