Jamb Physics 1978 Past Questions and Answers

Question 31:

• JAMB 1978

The electric supply from Kainji Dam is transmitted at high voltages of the order hundreds of kilovolts but is converted to domestic use of about 220 volts by

A. Commutators
B. Transistors
C. Valves and diodes
D. Rectifiers
E. Transformers

Question 32:

• JAMB 1978

Every house supplied with electricity is provided with a box of fuses so that

A. The consumption of electricity can be recorded
B. People residing in the house will not have an electric shock if they touch a live wire
C. The total current drawn from the mains can be limited
D. The voltage supply can be stabilized
E. It serves as a standby supply when there is a power failure

Question 33:

• JAMB 1978

An electric charge could be transmitted through

A. Wood, rubber and stone
B. Paper, clay and plastic
C. Glass, acid and cloth
D. The human body, water and metals
E. All of the above

Question 34:

• JAMB 1978

a guitar string is 75cm long. the wavelength of its fundamental note is

A. 75cm
B. 150cm
C. 37.5cm
D. 112cm
E. 50cm

Question 35:

• JAMB 1978

The boys are communicating with each other by stretching a string passing through a hole punched in the bottom of each of two tin cans. The physical principle employed is that sound travels

A. Mainly through air
B. Fainter in stretched string
C. Faster through gases than in solids and liquids
D. With greater ease through a string than in air
E. None of the above is correct