Electricity can flow either as direct or alternating current, and is used in homes to power electrical appliances.
Part of Combined ScienceElectricity
The power rating of electrical appliances can be used to calculate the cost of using them.
The following equation enables the number of units used to be calculated:
Number of units used = power rating in kW x time in hours
When using this equation it is important to remember that the power must be in kW and the time in hours.
Example
Calculate the cost of using a 2 kW heater for 6 hours if the price of a unit is 13p.
Time = 6 hours
Power rating = 2 kW
Number of units used = 2 kWh x 6 h = 12 kWh
total cost = number of units used 脳 cost per unit
= 12 kWh x 13p
= 156p
= 拢1.56
The cost of using the heater is 拢1 .56