49.
A perfect emitter or absorber of radiant energy is a -----.
A.
white body
B.
black
C.
red body
D.
conductor
Answer
50.Which
of the following types of waves needs a medium for propagation?
A.
Light waves
B.
Radio waves
C.
Sound waves
D.
X-rays
Answer
51.
Which of the following electromagnetic waves has the highest frequency?
A.
Infra-red rays
B.
X-rays
C.
Ultra-violet rays
D.
Radio waves
Answer
52.
When the human eye loses its power of accommodation, the defect is known as….
A.
astigmatism
B.
long-sightedness
C.
short-sightedness
D.
presbyopia
Answer
53.
A length of wire has a frequency of 255Hz when stretched by a force of 225N. If
the force increases to 324N, what is the new frequency of vibration?
A.488Hz
B.
356Hz
C.
306Hz
D.
512Hz
Answer
54.
A certain far-sighted person cannot see objects that are closer to the eye than
50cm clearly. Determine the power of the converging lens which will enable him
to see at 25cm.
A.
0.03D
B.
0.04D
C.
0.06D
D.
0.02D
Answer
55.
Which of the following electromagnetic waves has the highest frequency?
A.
infra-red rays
B.
X-rays
C.
ulta-violet rays
D.
radio waves
Answer
56.
When a red rose flower is observed in blue light, what does colour does the observer
see?
A.
magenta
B.
yellow
C.
blue
D.
red
Answer
57.
The eclipse of the sun occurs when the ….
A.
moon is not completely hidden in the earth`s shadow
B. moon`s umbra falls on some parts of the
earth
C. moon is between the sun and the earth
D. earth is between the sun and the moon
Answer
58.
A cannon is fired from town X. After how long is the sound heard at a town Y
4.95km away?
A.12s
B.
15s
C.
30s
D.
10s
[Velocity
of sound in air = 330m/s ]
Answer
59.
An image in a convex lens is upright and magnified 3 times. If the focal length
of the lens is 15cm, what is the object distance?
A.
16cm
B.
14cm
C.
10cm
D.
25cm
Answer
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