The table compares a halogen lamp and an LED lamp which produce the same intensity of light.
| Halogen lamp | LED lamp | |
|---|---|---|
| Power | 40 W | 0.008 kW |
| Lifetime | 3000 hours | 24,000 hours |
| Cost to buy | £2.00 | £6.00 |
| Cost to run over 1 year | £15.00 | £3.00 |
| Dimmable | Yes | No |
| Structure | Glass | Plastic |
State the power of the halogen lamp in kW.
Calculate the energy transferred by the LED lamp during its lifetime. Use the equation: energy transferred=power×time\text{energy transferred} = \text{power} \times \text{time}energy transferred=power×time Give your answer in kWh.
In 1 year, the halogen lamp transfers 75 kWh of energy. This costs £15.00. What is the cost of 1 kWh of electricity?
Calculate the number of halogen lamps a person must buy during the lifetime of one LED lamp.
Suggest one reason for and one reason against using LED lamps, using the data in the table.
One LED lamp has an efficiency of 0.35. In one second, the input energy transferred by the lamp is 20 J. Calculate the energy wasted by the lamp in one second. Use the equation: efficiency=useful output energy transferinput energy transfer\text{efficiency} = \frac{\text{useful output energy transfer}}{\text{input energy transfer}}efficiency=input energy transferuseful output energy transfer
The graph shows how the total cost of buying and using each lamp varies with the number of days each lamp is used.
A person buys an LED lamp. After how many days is the total cost of the LED lamp the same as the total cost of the halogen lamp?
The person uses the lamp for 100 days. How much money does the person save by buying and using the LED lamp instead of the halogen lamp?