Test Bite

You scored 5 out of 5

1. The useful energy transfer that happens in an electric lamp is:

You said: electricity → light

 Correct.

2. ‘Wasted energy’ becomes less useful because:

You said: it becomes increasingly spread out

 Correct.

3. Which equation can be used to calculate the efficiency of an energy transfer?

You said: efficiency = useful energy out ÷ total energy in

 Correct.

4. In a certain device, 25% of the energy is usefully transferred. The energy efficiency of this device is:

You said: 25%

 Correct.

5. A coal-fired power station is 40% efficient. This means that:

You said: 40% of the chemical energy stored in coal is transferred to electrical energy

 Correct.