Electronics and Communication Engineering questions and answers

Electronics and Communication Engineering Questions and Answers

Prepare for your Electronics and Communication Engineering exams/aptitude tests, assess your knowledge of electronics and communication equipment with these ECE questions and answers.

41.

In the circuit above, the function of resistor R and diode D are

A.

to limit the current and to protect LED against over voltage

B.

to limit the voltage and to protect LED against over current

C.

to limit the current and protect LED against reverse breakdown voltage.

D.

none of the above.

Correct answer is C

Resistance limits current and diode is reverse connected and therefore protects LED against reverse breakdown.

42.

Assertion (A): A p-n junction has high resistance in reverse direction.

Reason (R): When a reverse bias is applied to p-n junction, the width of depletion layer increases.

A.

Both A and R are true and R is correct explanation of A

B.

Both A and R are true but R is not a correct explanation of A

C.

A is true but R is false

D.

A is false but R is true

Correct answer is A

The increase in reverse resistance is due to widening of depletion layer.

43.

The amount of photoelectric emission current depends on

A.

frequency of incident radiation

B.

intensity of incident radiation

C.

both frequency and intensity of incident radiation

D.

none of the above

Correct answer is B

Only the intensity of incident radiation governs the amount of photoelectric emission.

44.

In an n channel JFET, the gate is

A.

n type

B.

p type

C.

either n or p

D.

partially n & partially p

Correct answer is B

Since channel is n type gate must be p type.

45.

In p-n-p transistor the current IE has two components viz. IEP due to injection of holes from p-region to n-region and IE due to injection of electrons from n-region to p-region. Then

A.

IEp and IEn are almost equal

B.

IEp >> IEn

C.

IEn >> IEp

D.

either (a) or (c)

Correct answer is B

Emitter is p-type in p-n-p transistor.

Therefore holes are majority carriers.