Physics Past Questions and Answers

The inside portion of part of a hollow metal sphere of diameter 20cm is polished. The portion will therefore form a

A Concave mirror of focal length 5cm
B Concave mirror of focal length 10cm
C Convex mirror of focal length 5cm
D Convex mirror of focal length 20cm

Question 22:

The velocities of light in air and glass are 3.0 x 10⁸ms^-1 and 2.0 x 10⁸ms^-1 respectively. If the angle of refraction is 30°, the sine of the angle of incidence is

A 0.33
B 0.50
C 0.67
D 0.75

Question 23:

An astronomical telescope is said to be in normal adjustment when the

A Eye is accommodated
B Focal length of objective lens is longer than that of eye piece
C Final image is at the near point of eye
D Final image is at infinity

Question 24:

Which of the following electromagnetic waves is least energetic?

A Infra-red rays
B X-rays
C Ultra-violet rays
D Gamma rays

Question 25:

Steel is more suitable for permanent magnet than iron because the former

A Is easily demagnetized by shaing vigorously
B Is an alloy of many metals
C Is easily magnetized by alternating current through one cycle
D Retains magnetism more than iron