A single-phase energy meter has a rating of 1200 revolutions per kilowatt-hour (kWh). If an electric appliance rated at 500 W operates continuously for 4 hours, how many revolutions will the meter complete?

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Solve this multiple-choice question and choose the correct option.

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Introduction / Context:Energy meters (also called watt-hour meters) measure the energy consumed by electrical loads. They are calibrated such that a fixed number of revolutions of the meter disc corresponds to one kilowatt-hour of electrical energy. This question involves computing the number of revolutions for a given power, time, and meter constant. Given Data / Assumptions: Meter constant: 1200 revolutions per 1 kWh. Load power: 500 W = 0.5 kW. Time of operation: 4 hours. Concept / Approach:Energy consumed (kWh) = Power (kW) × Time (hours). Number of revolutions = Energy consumed × meter constant. By substituting the given data, we can directly calculate the revolutions. Step-by-Step Solution: Step 1: Power = 500 W = 0.5 kW.Step 2: Time = 4 h.Step 3: Energy consumed = 0.5 × 4 = 2 kWh.Step 4: Revolutions = 2 × 1200 = 2400 revolutions. Verification / Alternative check: If load was 1 kW for 1 hour, energy = 1 kWh → 1200 revolutions. Our case is 2 kWh, so 2 × 1200 = 2400. This matches. Why Other Options Are Wrong: 1200 corresponds to 1 kWh, but here energy is 2 kWh.1800 and 2100 are arbitrary mismatches.1500 is not consistent with the meter constant. Common Pitfalls: Forgetting to convert watts to kilowatts or ignoring operating hours. Final Answer: 2400 revolutions

A single-phase energy meter has a rating of 1200 revolutions per kilowatt-hour (kWh). If an electric appliance rated at 500 W operates continuously for 4 hours, how many revolutions will the meter complete?

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