COMEDK · Physics · 19. Current Electricity
A \(500 \mathrm{~W}\) heating unit is designed to operate on a \(400 \mathrm{~V}\) line. If line voltage drops to \(160 \mathrm{~V}\), the percentage drop in heat output will be:
- A 74%
- B 84%
- C 75%
- D 85%
Answer & Solution
Correct Answer
(B) 84%
Step-by-step Solution
Detailed explanation
The power \(P\) consumed by a heating unit is given by the formula \(P = \dfrac{V^2}{R}\), where \(V\) is the voltage and \(R\) is the resistance of the heating element. Since the resistance \(R\) is constant, the power is proportional to the square of the voltage,…
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