Exercise related to Power
A 100 watt light bulb is on 24 hours a day
How much energy is used in a month?
E = 100 W x 24 hr/day x 30 days = = 0.1 KW x 720 hr = 72 KW-hours At $0.10/ 72 KW-hours, this costs $7.20.
( Also E = 100 J/s x 60 s/min x 60 min/hr 24 hr/day x 30 days = 100 x 60 x 60 x 24 x 30 J = 2.592 x 10 8 J (not a practical scale!) )