A resistor develops 400 J of thermal energy in 10 s when a current of 2 A is passed through it. Find its resistance.
Source: JAMB · 2024
A resistor develops 400 J of thermal energy in 10 s when a current of 2 A is passed through it. Find its resistance.
Explanation
Heat produced in a resistor: H = I²Rt.
Substitute: 400 = 2² × R × 10 = 40R.
R = 400 ÷ 40 = 10 Ω.
Check: power = 400 ÷ 10 = 40 W, and P = I²R = 4 × 10 = 40 W. It matches.
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