Question

Which produces more light: a 60W light bulb that is 5% efficent or a 30W light bulb that is 15% efficent? Explain.

Answer 1

Efficiency is defined as\[\eta = {\rm out \over i n}\]We are solving for output here. Therefore, \[\rm out = \eta \cdot i n\]where \(\eta\) will be the efficiency is decimal form (%/100) and "in" is the power rating of the bulb.