One unit is 1000 watt hour. Watt hour is energy and is product of watts and hour (time). If you switch on 100 watt lamp for 1 hour you will use only 100 watthours or one tenth of a unit. If you turn it on for 10 hours, you will consume 1 unit and will pay 10p. If you turn it on for 20 hours, you will consume 2 units and pay 20p. No charges if you do not turn it On at all. In a month, if you turn on the bulb say for 8 hours everyday on an average, you will consume 800*30/1000= 24 units and pay 240p. so if 100watt is left ON for 12 hours, you end up consuming 1.2 units and will be charged 12p
One unit is one kilowatt-hour.
Multiply power by time, then divide by 1000 to get kilowatts if the power was in watts.
100 x 12 = 1200 watt-hours; /1000 = 1.2 KwH = 1.2 Units.
1.2 x 10p = 12p.
100W * 12hours / 1000W * 10p = 12p
I dont think this is answerable without knowing your unit. The relevant SI units are Watts and seconds.
I don't know how to answer this question - I don't know which calculation to use? Please help- I have my Physics mock on Tuesday and I'm so stuck! Thank you
