Electrical Energy and Power - Jamb Physics Past Questions and Answers

Question 21:

• JAMB 1998

Electricity is supplied to a school along a cable of total resistance 0.5\(\Omega\) with the maximum current drawn from the mains as 100A. The maximum energy dissipated as heat for 1 hr is

A. 3.6 x 10³J
B. 5.0 x 10³J
C. 3.0 x 10⁵J
D. 1.8 x 10⁷J

Question 22:

• JAMB 1998

A transformer which can produce 8V from a 240v a.c. supply, has an efficiency of 80%. If the current in the secondary coil is 15A, calculate the current in the primary coil.

A. 0.625A
B. 1.600A
C. 2.500A
D. 6.250A

Question 23:

• JAMB 1999

A 3000W electric cooker is to be used on a 200V mains circuit. Which of the fuses below can be used safely with the cooker?

A. 2A
B. 5A
C. 10A
D. 20A

Question 24:

• JAMB 2000

An electric generator with a power output of 3.0KW at a voltage of 1.5KV distributes power along cables of resistance 20.0Ω. The power loss in the cables is

A. 80.0W
B. 40.0W
C. 10.0W
D. 0.1W

Question 25:

• JAMB 2000

The correct position for a fuse in the diagram above is

A. Between P and Q
B. Q
C. S
D. P