Energy Efficiency Flashcards
1
Q
What is energy efficiency?
A
Efficiency is a measure of how good a device is at transferring energy from one store to another.
2
Q
True or False? Energy efficiency has units.
A
False, it does not have units. It’s a number between 0 and 1 which can be converted into a percentage by multiplying it by 100.
3
Q
What is the equation used to calculate energy efficiency?
A
Energy efficiency = Useful energy output / Total energy input
4
Q
A light bulb transfers 300J of energy electrically. It converts 180J to light by radiation and 120J to thermal energy. Calculate the efficiency of the light bulb.
A
Efficiency = 180 / 300
= 0.6 or 60%
