Physics (AS & A Level) · Feb / March 2018 · Paper 12 · Question 15

An old-fashioned 60 W lamp converts 95% of its energy supply into heat. A 4.0 W modern lamp has the same power output of light as the old-fashioned lamp. What is the efficiency of the modern lamp?

1. A5.0%
2. B6.7%
3. C75%
4. D95%

As printed in the paper