set 10 MCQ Questions & Answers Detailed Explanation

Question : 1

A worker was working on the rail track. A boy at a distance holds his ear near the rail track. This boy was able to hear sound of the blow of workman twice. It is because of

a) The speed of sound is greater in air than in steel

b) Part of the sound wave is reflected between the rail tracks

c) The speed of sound is greater in steel than in air

d) His ears are at different distance from the source

Question : 2

Which one of the following is the mode of heat transfer in which warm material is transported so as to displace a cooler material ?

a) Convection only

b) Conduction only

c) Radiation

d) Both conduction and convection

Question : 3

Assertion (A):
A piece of copper and a piece of glass are heated to the same temperature. When touched, thereafter the copper piece appears hotter than the glass piece.
Reason (R):
The desity of copper is more than that of glass.
Code

a) Both (A) and (R) are true, but (R) is not the correct explanation of (A)

b) (A) is true, but (R) is false

c) Both (A) and (R) are true and (R) is the correct explanation of (A)

d) (A) is false, but (R) is true

Question : 4

Soap bubble looks coloured due to

a) interference

b) dispersion

c) reflection

d) Any one of these

Question : 5

Which of the following is used to find the depth of sea?

a) ECHO

b) RADAR

c) SONAR

d) None of these

Question : 6

Consider the following statements:

1. Light of longer wavelength are scattered much more than the light of shorter wavelength.
2. The speed of visible light in water is 0.95 times the speed in vacuum.
3. Radio waves are produced by rapidly oscillating electrical currents.
4. To detect the over speeding vehicles, police use the Doppler effect of reflected short radio waves.

a) 2 and 4

b) 1 and 2

c) 1 and 3

d) 3 and 4