Question

A lightbulb has a power of 100 W. and is used for 4 hours. A microwave has a power of 1200 W and is used for 5 minutes.

a. How much energy is used by the lightbulb?

b. How much energy is used by the microwave?

c. The lightbulb has an efficiency of 1.8%. How much heat energy does the lightbulb produce in 4 hours?

Answer 1

a) E=Nt=100*(4*3600)=1440000 J

b) E=1200*(5*60)=360000 J

c) Q=E*(100-1.8)/100=1414080 J