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A 5°C rise in temperature is observed in a conductor by passing a current. When the current is doubled the rise in temperature will be approximately

1. 10°C
2. 16°C
3. 20°C
4. 12°C

Correct answer: 20°C

Solution

The heat produced in a conductor is proportional to the square of the current (H ∝ I²). Doubling the current increases the heat by a factor of 4, so the temperature rise will also increase by a factor of 4. Thus, the new temperature rise is 5°C × 4 = 20°C.

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