How much would it cost to operate a 100-watt light bulb for 10 hours at a cost of 10 cents per kilowatt hour?

Question

How much would it cost to operate a 100-watt light bulb for 10 hours at a cost of 10 cents per kilowatt hour?

Answer 1

100 watt * 10 hours = 1000 watt hours = 1 kilowatt hour

1 kilowatt hour = 10 cents

it costs 10 cents

Answer 2

P = 100W = 0.1kW

t = 10 hr.

Energy = P t = 0.1kW * 10 hr = 1kW-hr

Cost = Energy * Cost/Energy = 1kW-hr * $0.10/kW-hr = $0.10