Electrical Energy and Power - Jamb Physics Past Questions and Answers

Question 51:

• JAMB 2012

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 52:

• JAMB 2012

A working electric motor takes a current of 1.5 A when the p.d across it is 250V. If its efficiency is 80%, the power output is

A. 300.0W
B. 469.0W
C. 133.0W
D. 4.8W

Question 53:

• JAMB 2012

The cost of running five 60 W lamps and four 100 W lamps for 20 hours if electrical energy cost #10.00 per kwh is

A. 280.00
B. 160.00
C. 120.00
D. 140.00

Question 54:

• JAMB 2012

The primary coil of a transformer has N turns and is connected to a 120 V a.c. power line. If the secondary coils has 1 000 turns and a terminal voltage of 1 200 volts, what is the value of N?

A. 120
B. 100
C. 1 000
D. 1 200

Question 55:

• JAMB 2013

A house has ten 40W and five 100W bulbs. How much will it cost the owner of the house to keep them lit for 10 hours if the cost of a unit is 5N?

A. N90
B. N50
C. N45
D. N5