Energy Transfer and Efficiency
Types of Energy
There are 10 types of energy which can be remembered using the phrase: Most Kids Hate Learning GCSE Energy Names
Kinetic - movement energy
Heat - kinetic energy in molecules, when things are hot
Gravitational Potential- energy you have if you are high up
Chemical - stored energy in things like batteries and food
Sound - molecules vibrating in waves
Electrical - electrons moving in a circuit
Elastic Potential - energy gained by stretching things
Law of Conservation of Energy
Energy cannot be created or destroyed; it is just transfered from one type to another.
eg. a Light bulb turns Electrical Energy into Light and Heat.
We can represent energy transfer using a Sankey Diagram. Here are the rules for drawing them:
1) All arrows must be labelled with their energy type, efficiency and number of Joules
2) All useful energy arrows are horizontal
3) All wasted energy arrows are vertical
4) The arrow width is proportional to its percentage of energy.
Efficiency can be calculated using the formula:
On the left is a Sankey diagram for a light bulb. It produces 10J of useful light energy and 90J of wasted heat energy.
Can you calculate the efficiencies?
You may find the following Phet simulation useful: