Electricity can flow either as direct or alternating current, and is used in homes to power electrical appliances.
Part of Physics (Single Science)Electricity
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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