Efficiency
You should know that energy can be 'wasted' during energy transfers, and you should be able to calculate the efficiency of a device.
Using this example of a light bulb we will now calculate the efficiency.
The equation to calculate efficiency is:
efficiency = ( useful energy transferred ÷ energy supplied ) × 100
The efficiency of the light bulb is (10 ÷ 100) × 100 = 10%.
This means that 10% of the electrical energy supplied is transferred as light energy (90% is transferred as heat energy).
The equation to calculate efficiency is:
efficiency = ( useful energy transferred ÷ energy supplied ) × 100
The efficiency of the light bulb is (10 ÷ 100) × 100 = 10%.
This means that 10% of the electrical energy supplied is transferred as light energy (90% is transferred as heat energy).