The useful energy transfer that happens in an electric lamp is
The correct answer is electricity → light.
1 of 9
Wasted energy' becomes less useful because
It becomes increasingly spread out.
2 of 9
Which equation can be used to calculate the efficiency of an energy transfer?
efficiency = useful energy out ÷ total energy in
3 of 9
In a certain device, 25% of the energy is usefully transferred. The energy efficiency of this device is:
25%
4 of 9
A coal-fired power station is 40% efficient. This means that:
40% of the chemical energy stored in coal is transferred to electrical energy.
5 of 9
The energy transferred by an electrical appliance can be calculated using this equation: energy = power × time How much energy is transferred by a 500 W electric drill in 30 seconds?
15,000J
6 of 9
A 250W computer is switched on for 4 hours. How many Units of electricity does it use?
A 250W computer is switched on for 4 hours. It would use 1 unit of electricity.
7 of 9
A 2 kW electric fire is switched on for 30 minutes. How many Units of electricity does it use?
A 2 kW electric fire is switched on for 30 minutes. It would use 1 unit of electricity.
8 of 9
If one Unit of electricity costs 10p, how much will 30 Units cost?
If one Unit of electricity costs 10p, 30 units would cost £3.
9 of 9
Other cards in this set
Card 2
Front
Wasted energy' becomes less useful because
Back
It becomes increasingly spread out.
Card 3
Front
Which equation can be used to calculate the efficiency of an energy transfer?
Back
Card 4
Front
In a certain device, 25% of the energy is usefully transferred. The energy efficiency of this device is:
Back
Card 5
Front
A coal-fired power station is 40% efficient. This means that:
Comments
No comments have yet been made