Which unit is commonly used to express energy consumption in household electrical devices?

Which unit is commonly used to express energy consumption in household electrical devices?

• A. Joule
• B. Newton
• C. Watt-hour
• D. Watt

Answer: (C)

Energy consumption is the amount of energy used over time. In household devices, you distinguish between how fast energy is used (power) and how much energy is used in total (energy). Power is measured in watts, which tells you the rate of energy use at a moment. To express the total energy used, you multiply that power by the time the device runs, giving watt-hours. Household energy bills are typically shown in kilowatt-hours, which are simply thousands of watt-hours. For example, a 60-watt lamp that runs for 8 hours uses 60 × 8 = 480 Wh, or 0.48 kWh. Joules are a general unit of energy, but not convenient for everyday household tracking; Newton is a unit of force and isn’t relevant to energy usage. So the unit most commonly used to express energy consumption in household devices is watt-hours.

Energy consumption is the amount of energy used over time. In household devices, you distinguish between how fast energy is used (power) and how much energy is used in total (energy). Power is measured in watts, which tells you the rate of energy use at a moment. To express the total energy used, you multiply that power by the time the device runs, giving watt-hours. Household energy bills are typically shown in kilowatt-hours, which are simply thousands of watt-hours. For example, a 60-watt lamp that runs for 8 hours uses 60 × 8 = 480 Wh, or 0.48 kWh. Joules are a general unit of energy, but not convenient for everyday household tracking; Newton is a unit of force and isn’t relevant to energy usage. So the unit most commonly used to express energy consumption in household devices is watt-hours.