Question

A 150 W driveway light produces 9.3 × 104 J of light energy over a 4.0 h period. If the light uses 2.06 × 106 J of energy in the 4.0 h, then what is its efficiency? Show all your work.

Answer 1

4.5%

Step-by-step explanation:

efficiency = energy out / energy in

e = 9.3×10⁴ J / 2.06×10⁶ J

e = 0.045