Efficiency
When a device or object is going through an energy change, some of the energy that is inputted is TRANSFERRED USEFULLY and some is DISSIPATED or wasted.
Efficiency is a ratio of the amount of useful energy that’s given out to the total amount of energy that was originally put in. The equation for this is:
You can also rewrite the equation using power instead of energy to give you:
You can convert efficiency into percentages by multiplying by 100. For this example, this would give:
0.333 x 100 = 33.3%
Improving Efficiency
- The efficiency of a device can be improved by REDUCING wasted energy transfers.
- They waste energy mainly due to:
- Friction between their moving parts
- Air resistance
- Electrical resistance
- Sound
- Most of these lead to THERMAL energy being dissipated into the SURROUNDINGS. If you can minimise these, you can IMPROVE the EFFICIENCY of a device.