TRB Physics Question Bank - 4

Question: 16

Free electrons are always in ____

(A) Random motion

(B) Linear motion

(C) Vibrational motion

(D) Rotational motion

Question: 17

The number of electric lines of force per unit area at right angles to the lines is proportional to

(A) electric field strength

(B) density of the medium

(C) square of electric potential

(D) permittivity of the medium

Question: 18

A permanent magnet repels

(A) paramagnetic substance only

(B) body paramagnetic and diamagnetic substances

(C) diamagnetic substance only

(D) ferromagnetic substance only

Question: 19

Nights are cooler in the deserts because

(A) the sky is generally cloudy

(B) the sky is generally clear

(C) sand radiates heat less quickly as compared to earth

(D) sand radiates heat more quickly as compared to earth

Question: 20

A ray of light travelling in air falls obliquely on the surface of a calm pond. It will

(A) Turn back on its original path

(B) Go into the water without deviating from its path

(C) Deviate away from the normal

(D) Deviate towards the normal