Question 36:

• JAMB 1978

A potential difference of 6v is used to produce a current of 5A for 200s through a heating coil. The heat produced is

A. 4800 cal
B. 6000 cal
C. 2400J
D. 240k cal
E. 6000J

Question 37:

• 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 38:

• 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 39:

• 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 40:

• 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