Calculating the Cost of Electricity (WJEC GCSE Physics)

In the month of January, a 3 bedroom household used 284 kWh of electricity, and 1366 kWh of gas.

The household's tariff details are listed below.

• Electricity unit price: 26.47 p/kWh
• Electricity standing charge: 51.38 p/day
• Gas unit price: 7.00 p/kWh
• Gas standing charge: 26.16 p/day

Calculate the total price of the energy bill for the month of January.

The month of January has 31 days. Ignore the cost of VAT tax.

 

Answer:

Step 1: List the known quantities

• Electricity used = 284 kWh
• Electricity unit price = 26.47 p/kWh
• Gas used = 1366 kWh
• Gas unit price = 7.00 p/kWh
• Electricity standing charge = 51.38 p/day
• Gas standing charge = 26.16 p/day

 

Step 2: Write out the equation for calculating the cost of energy

Cost = units used × cost per unit

 

Step 3: Calculate the cost of the electricity used

• Convert pence (p) to pounds (£) by dividing by 100 and rounding to the nearest pence

 

Step 3: Calculate the cost of the gas used

 

Step 4: Calculate the total standing charge for electricity

total standing charge electricity = standing charge per day × number of days

 

Step 5: Calculate the total standing charge for gas

 

Step 6: Add all the individual costs together to find the total cost of the bill

Total cost of bill = cost of electricity + cost of gas + total standing charge electricity + total standing charge gas