Waec Physics 1990 Past Questions and Answers

Question 21:

• WAEC 1990

Heat transfer by convection in a liquid is due to the

A. Translatory motion of the molecules of the liquid
B. Increased vibration of the molecules of the liquid about their mean positions
C. Expansion of the liquid as it is heated
D. Latent heat of vaporization of the liquid
E. Ability of the liquid to evaporate at all temperatures

Question 22:

• WAEC 1990

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
E. Keeping it in a closed wooden box

Question 23:

• WAEC 1990

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
E. Mechanical wave

Question 24:

• WAEC 1990

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
E. 330.00m

Question 25:

• WAEC 1990

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
E. The amplitude of the vibrating fork is increased.