A household has two lighting options: traditional filament bulbs with a power-rating of 60 W, or LED bulbs with a power-rating of 8 W, both producing the same brightness. Explain why replacing filament bulbs with LED bulbs reduces the number of kilowatt-hours used by the household each month.

A kilowatt‑hour (kWh) is the unit of energy used to measure how much electrical energy a household consumes.

The power rating of a light bulb (60 W for a filament bulb, 8 W for an LED) tells how much electrical energy is converted into light and heat per unit time.

A filament bulb converts most of its 60 W into heat rather than useful light, so a large part of the energy is wasted.

An LED uses only 8 W to give the same brightness, so it transfers less energy overall. Over the same period of use, the LED therefore consumes fewer kWh, reducing the household’s monthly energy usage.