Physics 9702 · AS & A Level · Energy conservation

Energy conservation — practice question

An older-style $60\,$W lamp changes $95\%$ of its energy supply into heat. A modern $4.0\,$W lamp produces the same light power output as the older lamp. What is the efficiency of the modern lamp?

  • A$5.0\%$
  • B$6.7\%$
  • C$75\%$
  • D$95\%$

Worked solution & mark scheme

This 1-mark question has a full step-by-step worked solution and mark scheme.

  • Full mark scheme, point by point
  • Step-by-step worked solution
  • Write your answer & get it marked instantly by AI