PG TRB Physics Study Materials 2020 - 2021 - 1

Question: 1

Which one among the following satellites is used to reflect the radio signals back to the Earth?

(A) Active satellite

(B) Passive satellite

(C) Natural satellite

(D) None of these

Ans: B

Passive satellite

Question: 2

Who invented the laser?

(A) Sir Frank Whittle

(B) Charles H. Townes

(C) Fred Morrisson

(D) Seymour Cray

Ans: B

Charles H. Townes

Question: 3

Lumen is the unit of

(A) Luminous flux

(B) Luminous intensity

(C) Both

(D) None of these

Ans: A

Luminous flux

Question: 4

Rain drops assume spherical shape due to

(A) Gravitational force

(B) Centripetal force

(C) Centrifugal force

(D) Surface tension

Ans: D

Surface tension

Question: 5

The maximum displacement of a particle in the upward direction is

(A) Node

(B) Crest

(C) Wavelength

(D) Trough  

Ans: B


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