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Electronics and Communication Engineering - Electromagnetic Field Theory

Exercise : Electromagnetic Field Theory - Section 4
31.
Determine the transistor capacitance of a diffused junction varicap diode of a reverse potential of 4.2 V if C(0) = 80 pf and VT = 0.7 V
42 pf
153.03 pf
13.33 pf
Data inadequate
Answer: Option
Explanation:

, Here n = for diffused junction

.

32.
At room temperature the barrier potential in a silicon diode is
0.1 V
0.3 V
0.7 V
1 V
Answer: Option
Explanation:

This 0.7 V is also called cut in voltage. When forward voltage is 0.7 V or less there is no current.

33.
The cut in voltage of a diode is nearly equal to
applied forward voltage
applied reverse voltage
barrier potential
none of the above
Answer: Option
Explanation:
No answer description is available. Let's discuss.
34.

Assertion (A): In a BJT base current is very small.

Reason (R): In a BJT recombination in base region is high.

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:

Recombination in base region is very low.

35.
A reverse voltage of 18 V is applied to a semiconductor diode. The voltage across the depletion layer is
0 V
0.7 V
about 10 V
18 V
Answer: Option
Explanation:

Almost whole of reverse voltage is across depletion layer.

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