1990 - WAEC Physics Past Questions and Answers - page 3
21
Which of the following is not a suitable method for reducing loss of heat from a piece of hot iron?
A
Wrapping it in cotton wool
B
painting it black
C
Placing it in a vacuum
D
Placing it on rubber supports
correct option: b
Users' Answers & Comments22
When the direction of vibration of the particles of a medium is perpendicular to the direction of travel of a wave the wave transmitted is known as
A
sound wave
B
transverse wave
C
longitudinal wave
D
stationary wave
correct option: b
Users' Answers & Comments23
A bat emits a sound wave at a speed of 1650.0ms-1 and receives the echoes 0.15s later. Calculate the distance of the bat from the reflector
A
8.75m
B
16.50m
C
87.75m
D
123.75m
24
A tuning fork sounds louder when its stem is pressed against a table top than when held in air because
A
a larger mass of air is set vibrating by the table top
B
the whole table vibrates in resonance
C
the whole table has acquired a larger frequency
D
the fork and table have the same frequency
correct option: c
Users' Answers & Comments25
Which of the following is/are characteristics of sound? I Pitch II. Loudness III. Quality IV Noise
A
I only
B
II only
C
I and II only
D
l, II and III only
correct option: d
Users' Answers & Comments26
The diagram above represents part of a wave motion in air. If the wave travels with a speed of 300ms-1calculate the frequency of the wave.
A
360Hz
B
300Hz
C
250Hz
D
150Hz
27
Which of the following is/are necessary for the production of interference with two wave trains? I. The sources must be close to each other. II The waves must have the same frequency. III. The waves must have the same amplitude. IV. The waves must travel with the speed of light.
A
I, II and IV only
B
I, II and III only
C
I and II only
D
II, III and IV only
correct option: b
Constructive and destructive interference result from the interaction of waves that are correlated or coherent with each other, either because they come from the same source or because they have the same or nearly the same frequency.
28
A stone is dropped into the middle of a pool of water. Which of the following statements is/are correct? I, Spherical waves are set up in the water. II. The water moves outwards to the sides of the pool. III. Energy is transmitted outwards from the centre of disturbance
A
I only
B
II only
C
III only
D
I and III only
correct option: d
Users' Answers & Comments29
A concave mirror of radius of curvature 20cm has a pin placed at 15cm from its pole. What will be the magnification of the image formed?
A
4.00
B
2.00
C
1.33
D
1.50
correct option: b
1/U + 1/V = 1/f
f = r/2 = 10cm; 1/15 + 1/v = 1/10
v = 30 = m = v/u = 2
Users' Answers & Commentsf = r/2 = 10cm; 1/15 + 1/v = 1/10
v = 30 = m = v/u = 2
30
Where will the image of the object OB shown in the diagram above be located after reflection from the mirror?
A
At F
B
Beyond C
C
Between O and P
D
Between P and F
correct option: d
Users' Answers & Comments