The commercial unit of electric energy is:

Question

The commercial unit of electric energy is:

1. A. Watt
2. B. Kilowatt
3. C. Kilowatt hour (Correct answer)
4. D. Kilovolt

Correct Answer

Option C — Kilowatt hour

Detailed Solution & Explanation

The correct answer is Kilowatt hour.

Key Points

• The commercial unit of electrical energy is the kilowatt hour (kWh), commonly called one unit on an electricity bill.
• Watt and kilowatt are units of power (the rate of energy use), not of energy, and kilovolt measures potential difference.
• 1 kWh = 3.6 × 10⁶ joules.

Additional Information

• The joule is the SI unit of energy; the kilowatt hour is simply a practical, larger unit for billing.
• Energy consumed = power (kW) × time (hours), so a 1,000 W heater running for one hour uses exactly one unit.
• Keep the pair straight: power is the rate, energy is the total — the same distinction as speed against distance.