Jamb Physics 2012 Past Questions and Answers

Question 91:

• JAMB 2012

A cell of internal resistance r supplies current to a 6.0Ω resistor and its efficiency is 75%. Find the value of r.

A. 4.5Ω
B. 1.0Ω
C. 8.0Ω
D. 2.0Ω

Question 92:

• JAMB 2012

A resistance R is connected across the terminal of an electric cell of internal resistance 2Ω and the voltage was reduced to 3/5 of its nominal value.
The value of R is

A. 3 Ω
B. 2 Ω
C. 1 Ω
D. 6 Ω

Question 93:

• JAMB 2012

A student is at a height 4m above the ground during a thunderstorm. Give that the potential difference between the thundercloud and the ground is 10⁷v, the electric field created by the storm is

A. 2.0 * 10⁶ NC ^-1
B. 2. 5 * 10⁶ NC ^-1
C. 1.0 * 10⁷ NC ^-1
D. 4.0 * 10⁷ NC ^-1

Question 94:

• 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 95:

• 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