A heating element has a resistance of 100 Ω at room temperature. When it is connected to a supply of 220 V , a steady current of 2 A passes in it and temperature is 500 o C more than the room temperature. The temperature coefficient of resistance of the heating element is

Question

A heating element has a resistance of 100 Ω at room temperature. When it is connected to a supply of 220 V , a steady current of 2 A passes in it and temperature is 500 o C more than the room temperature. The temperature coefficient of resistance of the heating element is, 5 × 10 - 4 o C - 1, 2 × 10 - 4 o C - 1, 1 × 10 - 4 o C - 1, 0.5 × 10 - 4 o C - 1

MARKS App · Accepted Answer

Resistance of heating element after temperature increases by 500 o C = 220 2 = 110 Ω (from Ohm's law). The new resistance is related to the temperature coefficient of the heating element as 110 = 100 ( 1 + α 500 ) α = 10 100 × 500 ⇒ α = 2 × 10 - 4 ° C - 1

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