A nichrome wire used as a heater coil has the resistance of 2 £2/m. For a heater of 1 kW at 200 V, the length of wire required will be_____________?
Correct answer: D. 20 m
- A. 80 m
- B. 60 m
- C. 40 m
- D. 20 m
Explanation
At 1 kW and 200 V, the heater resistance is R = V²/P = 200²/1000 = 40 Ω. With 2 Ω per metre, the required length is 40/2 = 20 m.
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