A family is choosing between a filament lamp and an LED lamp. Both lamps give out the same amount of light.
The Table shows information about the two lamps.
Table
| Lamp | Power in W\text{W}W | Useful energy transferred by light each second in J\text{J}J | Lifetime in hours | Cost to buy in £ |
|---|---|---|---|---|
| filament lamp | 60 | 3 | 1000 | 1.00 |
| LED lamp | 8 | 3 | 25 00025\ 00025 000 | 5.00 |
Compare the two lamps and explain which lamp the family should choose.
Use calculations of efficiency and wasted energy in your answer.
50 exam-style questions on OCR GCSE Physics 7.2 Power and efficiency, covering 7.2.1 Dissipation of energy, 7.2.2 Energy transfers in domestic devices, 7.2.3 Power ratings of domestic appliances, 7.2.4 Efficiency of energy transfers, 7.2.5 Ways to increase efficiency, 7.2.6 Reducing unwanted energy transfers, and 7.2.7 Thermal conductivity and the cooling of buildings. Each one has a worked solution and a mark scheme showing where the marks go.