2005 - WAEC Physics Past Questions and Answers - page 3
21
The energy required to change a solid to liquid at constant temperature is called
A
thermal capacity
B
has lower specific heat capacity
C
latent heat of fusion
D
latent heat of vaporisation
correct option: c
Users' Answers & Comments22
Which of the following statements about boiling and evaporation at atmospheric pressure is correct?
A
evaporation and boiling of water take place at 100o
B
evaporation of water takes place at a temperature greater than 100oC, while boiling takes place at 100oC
C
evaporation of water takes place at 100oC while boiling takes place at a higher temperature
D
boiling takes place at 100o while evaporation my take place at temperatures lower than 100oC
correct option: d
Users' Answers & Comments23
Which of the following statements is correct?
A
the density of a liquid decreases when it expands
B
the density of a liquid increases when the liquids are heated
C
the real expansivity of a liquid is less than its apparent expansivity
D
a liquid changes to solid when heated to a sufficiently high temperature
correct option: a
Users' Answers & Comments24
The pressure exerted by a given mass of gas in a container
A
decreases if the container is heated
B
increases if the molecules of the gas move faster
C
increases if the container is doubled
D
decreases as the kinetic energy of the gas molecules inceases
correct option: b
Users' Answers & Comments25
Which of the following statements about a progressive mechanical wave is correct?
A
it can be a plane polarised
B
its energy is localised at specific points of its profile
C
it does not require a material medium for its propagation
D
its frequency remains constant as it travels between different media
correct option: d
Users' Answers & Comments26
The distance between two points in phase on a progressive wave is 5cm. If the sped of the wave is 0.2ms-1, calculate its period
A
4.00s
B
2.50s
C
0.25s
D
0.04s
correct option: c
F = \(\frac{v}{\lambda} = \frac{0.2}{5 \times 10^{-2}} = 4Hz\)
T = \(\frac{1}{f} = \frac{1}{4} = 0.25s\)
Users' Answers & CommentsT = \(\frac{1}{f} = \frac{1}{4} = 0.25s\)
27
Radio waves travel in air at 3.0 x 108ms-1. If the waves enter water of refractive index \(\frac{4}{3}\), calculate the speed of radio waves in water
A
4.33 x 108ms-1
B
4.00 x 108ms-1
C
2.25 x 108ms-1
D
1.33 x 108ms-1
correct option: c
\(_an_w = \frac{4}{3} = \frac{\text{speed of light in air}}{\text{speed of light in water}}\)
\(\frac{4}{3} = \frac{3 \times 10^8}{x}\)
x = \(\frac{9 \times 10^4}{4}\)
= 2.25 x 108m/s
Users' Answers & Comments\(\frac{4}{3} = \frac{3 \times 10^8}{x}\)
x = \(\frac{9 \times 10^4}{4}\)
= 2.25 x 108m/s
28
The amplitude of a wave is the
A
distance travelled by the wave in a complete cycle of its motion
B
maximum diplacement of the wave particle from the equilibrum position
C
separation of two adjacent particles vibrating in a phase
D
distance between two successive troughs of the wave
correct option: b
Users' Answers & Comments29
Which of the following optical instruments does not depend on the use of plane mirrors?
A
kaleidoscope
B
simple microscope
C
sextant
D
simple periscope
correct option: b
Users' Answers & Comments30
A ray of light is incident normally on a plan mirror. If the incident ray is kept fixed while the mirror is rotated through an angle of 30o, determine the initial and final angles of reflection respectively
A
0o and 60o
B
90o and 30o
C
0o and 30o
D
90o and 60o
correct option: d
Users' Answers & Comments