Physics(General Knowledge > General Science ) Questions and answers for exam Preparation

General Knowledge > General Science

PHYSICS MCQs

Total Questions : 3767 | Page 4 of 377 pages

Question 31. Sound of frequency below 20 Hz is called

audio sounds
infrasonic
ultrasonic
supersonics

Discuss Question

Answer: Option B. -> infrasonic

Question 32. On a clean glass plate a drop of water spreads to form a thin layer whereas a drop of mercury remains almost spherical because:

mercury is a metal.
density of mercury is greater than that of water.
cohesion of mercury is greater than its adhesion with glass.
cohesion of water is greater than its adhesion with glass.

Discuss Question

Answer: Option C. -> cohesion of mercury is greater than its adhesion with glass.

Question 33. Stars twinkle because

the intensity of light emitted by them changes with time.
the distance of the stars from the earth changes with time.
the refractive index of the different layers of the earth's atmosphere changes continuously.
None of these

Discuss Question

Answer: Option C. -> the refractive index of the different layers of the earth's atmosphere changes continuously.

Question 34. Suitable impurities are added to a semiconductor depending on its use. This is done in order to

increase its life
enable it to withstand higher voltages
increase its electrical conductivity
increase its electrical resistivity

Discuss Question

Answer: Option C. -> increase its electrical conductivity

Question 35. It takes much longer to cook food in the hills than in the plains, because

in the hills the atmospheric pressure is lower than that in the plains and therefore water boils at a temperature lower than 100oC causing an increase in cooking time
due to low atmospheric pressure on the hills, the water boils at a temperature higher than 100oC and therefore water takes longer to boil
in the hills the atmospheric density is low and therefore a lot of heat is lost to the atmosphere
in the hills the humidity is high and therefore a lot of heat is absorbed by the atmosphere leaving very little heat for cooking

Discuss Question

Answer: Option A. -> in the hills the atmospheric pressure is lower than that in the plains and therefore water boils at a temperature lower than 100oC causing an increase in cooking time

Question 36. Moment of inertia is: