Electrician Red Seal · Question
A heating element in an industrial oven rated for 240 V, 3 kW is suspected of being faulty. An electrician isolates the element and measures its resistance using an ohmmeter. What approximate resistance reading should they expect from a healthy heating element?
Resistance can be calculated using Ohm's Law and the power formula: P = V^2 / R, therefore R = V^2 / P. For a 240 V, 3 kW (3000 W) element, R = (240 V)^2 / 3000
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Question: A heating element in an industrial oven rated for 240 V, 3 kW is suspected of being faulty. An electrician isolates the element and measures its resistance using an ohmmeter. What approximate resistance reading should they expect from a healthy heating element?
Answer options:
- Approximately 0 Ω (short circuit) ✅ Approximately 19.2 Ω
- Approximately 80 Ω
- An open circuit (infinite resistance)
Correct answer: Approximately 19.2 Ω
Explanation: Resistance can be calculated using Ohm's Law and the power formula: P = V^2 / R, therefore R = V^2 / P. For a 240 V, 3 kW (3000 W) element, R = (240 V)^2 / 3000 W = 57600 / 3000 = 19.2 Ω. Readings significantly different from this would indicate a faulty element (e.g., open circuit, short).
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