kWh Costs Question
Look at the table of data below. For the hairdryer, notice that both power and time aren't always in the "expected" units of kW and h.
|Object||Power||Time used||Units used (kWh)||Cost (p)
|hairdryer||1·2 kW||30 minutes||0·6||4·8 p|
|light bulb||100 W||20 hours|| || |
|microwave oven||800 W||45 minutes|| || |
|Assume 1 kWh of energy costs 8 p|
For the hairdryer, remember that 60 minutes = 1 hour, so 30 minutes = 0·5 hours. We must use this to find the units (kWh) used.
See if you can work out the units used, and the cost of running, the light bulb and microwave oven.