1000+ Materials Science Objective Questions and Answers Pdf - 1

Question: 1

The function of the commutators in a DC machine is

(A) to change the alternating voltage to direct voltage

(B) to change alternating current to direct current

(C) to improve commutation

(D) for easy speed control

Ans: B

to change alternating current to direct current

Question: 2

A universal motor

(A) can run for longer durations without noise

(B) can run without slip

(C) can run at speeds varying from zero to high values

(D) can run on AC as well as DC

Ans: D

can run on AC as well as DC

Question: 3

Sapphire is used for

(A) x-ray absorption

(B) tips of phonographs

(C) recording heads of tape recorders

(D) meser generation

Ans: B

tips of phonographs

Question: 4

The advantage of electric braking is

(A) motor continues to remain loaded during braking

(B) it avoids wear of track

(C) more heat is generated during braking

(D) it is instantaneous

Ans: B

it avoids wear of track

Question: 5

The ratio of the frequencies of two tones is called a

(A) musical scale

(B) harmonics

(C) overtone

(D) beat

Ans: A

musical scale

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