Cost of electricity
Electricity companies bill customers for the electrical energy they use.
A joule is much too small a unit of energy and so the electricity companies use units called kilowatt-hours, kWh.
Domestic electricity meters measure the number of units of electricity used in a home or other building.
The more units used, the greater the cost.
The cost of the electricity used is calculated using this equation:
total cost = number of units used × cost per unit
The cost per unit is set by the electricity company, for example 14.78 p per kWh.
This means that each unit of electricity costs 14.87 p.
An electricity bill has two important numbers: present meter reading and previous meter reading.
The number of units used is the difference between these two readings.
Present reading = 40745 kWh
Previous reading = 39990 kWh
Number of units used = present meter reading - previous meter reading
= 40745 – 39990
= 755 kWh
total cost = number of units used × cost per unit
= 755 x 14.78 p
= 11159 p
The cost of electricity used is £111.59
Question
Use the following information to calculate the cost of electricity used.
Previous reading = 37070 kWh
Present reading = 38217 kWh
Units at 14.78p per kWh.
Number of units used = present meter reading - previous meter reading
= 38217 – 37070
= 1147 kWh
total cost = number of units used × cost per unit
= 1147 x 14.78p
= 16953 p
= £169.53
The cost of electricity used is £169 .53.