Using Energy

Question	Answer
What form of energy does a compressed spring have ?	Elastic potential energy.
Where does the chemical energy stored in your muscles come from ?	From the food that you eat.
What energy transfers take place when you turn on a torch ?	Chemical to electrical to light and transfer by heating.
In terms of energy, what happens when you burn a fuel ?	Chemical energy in the fuel is transferred to the surroundings, which get warmer.
What happens to the wasted energy in a light bulb ?	It is transferred to the surroundings which get warmer.
Why should we talk about energy being 'wasted' not being 'lost' ?	Because the laws of conservation tells us that energy cannot be destroyed.
In a light bulb, for every 25 joules of energy that are supplied to the bulb, 5 joules are usefully transferred into light energy. What is the efficiency of the light bulb ?	The efficiency is 0.2 or 20%.
A machine is adjusted so that it wastes less energy because of friction. What happens to the Efficiency of the machine ?	The efficiency increases.

Resource summary

	Created by nadine pownall over 8 years ago