An electric heating element rated at 2,000 W is designed to operate on a 200 V mains electrical supply. What is the operating electrical resistance of the element?
Answer and explanation
Correct answer: A. 20 Ī©
- Step 1: Relate power, voltage, and resistance: P = VĀ² / R. Step 2. Rearrange: R = VĀ² / P. Step 3. Compute: R = 200Ā² / 2000 = 40,000 / 2000 = 20 Ī©. Answer: 20 Ī©. Why not the others: 10 Ī© is the current (I = P/V = 10 A); 40 Ī© doubles the resistance; 100 Ī© is an arbitrary guess.
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