1. The problem statement, all variables and given/known data Which is more efficient, or has the highest lm/W, a lower- or higher-power light bulb? To find out, look at bulbs and record the power and lumens. 2. Relevant equations Lumen, lm, = P or luminous flux. 3. The attempt at a solution Power of the light bulbs would be the number of watts, correct? I am confused as to how to calculate the lumens of a light bulb. My teacher said that we can just look at bulb boxes at a store, so I know no measuring of surfaces is involved. Thanks in advance.