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WAEC Physics 2021 Paper

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Question : 23

Total: 50

A current of 2A passes through a wire of resistance 4Ω for 3 minutes. Calculate the energy lost.

960J
1440J
2880J
48J

Solution:

Concept:

Energy lost in a resistor is the electrical energy converted to heat, given by

E = I^2 R t

.

Explanation:

Current,

I = 2\,A

.

Resistance,

R = 4\,\Omega

.

Time,

t = 3

minutes

= 3 \times 60 = 180\,s

.

Energy lost,

E = I^2 R t

.

E = (2)^2 \times 4 \times 180

.

E = 4 \times 4 \times 180 = 2880\,J

.

Answer:

The energy lost is

2880\,J

, which is option C.

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