POWER & ENERGY — Identify the correct quantity. Question: Kilowatt (kW) is a unit used to measure which physical quantity?

Introduction / Context:
Power and energy are frequently confused in everyday language. Kilowatt (kW) and kilowatt-hour (kWh) appear on appliance labels and electricity bills, respectively. This question checks whether you can separate instantaneous rate (power) from accumulated quantity (energy).

Given Data / Assumptions:

• Watt (W) is the SI unit of power; kilo- denotes 10^3.
• Energy in SI is joule (J); in power billing, energy is often reported in kWh.
• “Electricity” is a loose term and not a unit/quantity by itself.

Concept / Approach:
Power is the rate at which work is done or energy is transferred per unit time. 1 W = 1 J/s. Therefore, 1 kW = 1000 J/s. Energy over time uses watt-hours: energy (Wh) = power (W) * time (h). Distinguishing these clarifies why devices list kW (capacity/rating) while meters total kWh (consumption).

Step-by-Step Solution:
Identify quantity: kW = 10^3 watts.Recall: power P = energy/time.Therefore, kW measures power (rate), not energy.Relate: energy used E = P * t, often shown in kWh.

Verification / Alternative check:
If a heater is rated 2 kW and runs for 3 hours, energy = 2 kW * 3 h = 6 kWh. Rating is in kW (power), consumption is in kWh (energy), confirming the distinction.

Why Other Options Are Wrong:
A) Work (energy) is the result, measured in J or kWh, not kW.C) “Electricity” is not a unit; too vague.D) Current is measured in ampere (A).E) Energy is in joule or kilowatt-hour, not kilowatt.

Common Pitfalls:
Reading kW on a bill and assuming it is energy. Remember: kW (rate) vs kWh (amount).

Final Answer:
power