2012 - WAEC Physics Past Questions and Answers - page 3

21
A piece of copper of mass 20g at a temperature of 110oC was dropped into a mixture of ice and water at 0oC. If the final steady temperature of the mixture is 0oC . Calculate the amount of ice that melted [Specific heat capacity of copper = 0.4 Jg-1k-1, specific latent heat of fusion of ice = 330Jg]
A
0.37g
B
0.60g
C
2.40g
D
2.70g
22
Which of the following factors decreases the rate of evaporation of a liquid?
A
increase in pressure over the liquid
B
lowering the boiling point
C
decreasing in humidity
D
wind
23
When two waves are superimposed on each other, the following occurrences are possible, except
A
nodal lins
B
anti nodal lines
C
stationary waves
D
dispersion
24
Which of the following properties of waves is exclusive to transverse waves?
A
reflection
B
interference
C
diffraction
D
polarization
25
An object of height 2.5cm is places 20cm from a convex mirror of focal length 10cm. Calculate the height of its image
A
2.5 cm
B
3.0cm
C
5.0cm
D
25.0cm
26
A to eater to glass to air to water to glass to air. Given that the refractive index for light passing from air to water is 43 and air to glass is 32, calculate the refractive index of glass relative to water
A
0.50
B
0.67
C
0.75
D
1.13
27
An object is placed at a point X between the focal point F and the optical centre C of a diverging lens. If F is the focal point on the other side of the lens, the image of the object is formed between
A
F and X
B
X and C
C
C and F
D
F and 2F
28
An object is placed 10cm from a converging lens of foal length 15cm. Calculate the magnification of the image formed
A
3.0
B
1.5
C
0.6
D
0.3
29
A telescope is said to be in normal adjustment when the
A
focal length of he objective is greater than that of the eyepiece
B
focal length of the eyepiece is greater than that of the objective
C
focal length of the eyepiece is equal to that of the objective
D
objective focal point coincides wih that of the eyepiece
30
The sound heard by a person after the reflection of the sound generated by him is called
A
reverberation
B
resonance
C
echo
D
audibility
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