How much energy does a 60.0 w light bulb use in half an hour? is the light bulb is 12% efficient, how much thermal energy does it generate?

(a) The power of the bulb is P=60.0 W. Half an hour corresponds to a time of

so the energy used by the bulb during this time is


(b) The efficiency of the bulb is 12%, it means that it converts only 12% of the input energy into thermal energy, so the thermal energy is