The smart way to improve grades

Comprehensive & curriculum aligned

Affordable pricing from £10/month

Energy Cost

In this worksheet, students will learn about domestic use of fuel and how the cost is calculated for bills.

'Energy Cost' worksheet

Key stage:  KS 3

Curriculum topic:  Physics: Energy

Curriculum subtopic:  Calculation of Fuel Uses and Costs

Difficulty level:  

down

Worksheet Overview

QUESTION 1 of 10

When an electrical appliance is on and working, it uses electricity from the mains supply. Electrical energy is transferred from the mains to the appliance. The rate at which energy is transferred is measured in kilowatt hours (kWh). It can be calculated by multiplying the appliance power with the time it is being used.

 

energy transferred  =  power  ×  time

 

Note that since the unit for energy transferred to an appliance is kWh, when using the equation, you must make sure power is in kW and the time is converted into hours.

 

 

Electricity meters (see diagram below) are used at home to measure the energy transferred to all electrical appliances used at that particular house or building. The total cost is calculated using this formula:

 

total cost  =  number of units  ×  cost per unit

 

In the formula one unit is 1 kWh.

 

 

It is essential that energy is used efficiently by everyone nowadays, as excessive use causes more pollution to the environment and costs more. All appliances waste some energy when on, so only a proportion of the energy is utilised for the actual intended use. For example, a light bulb uses electricity when lit, but some of the output energy is heat, which is not actually needed from a light bulb. Heat is wasted into the environment. The more input energy (electricity) is utilised by an appliance for the intended use, the more efficient an appliance is. 

Sankey diagrams show the input and output energy of appliances; you will see the Sankey diagram for a light bulb below. The electrical energy transferred to the light bulb is 100 J. 75 J are actually converted to light energy, which is the intended use of a light bulb. 25 J are wasted as heat.

What type of energy is used by most appliances at home?

heat

kinetic

electrical

What is the unit of the energy transferred to electrical appliances by mains electricity?

J

W

kWh

Calculate the energy transferred to a 2 kW appliance over 3 hours.

1 kWh

5 kWh

6 kWh

Calculate the energy transferred to a 500 W appliance over 3 hours.

1500 kWh

1.5 kWh

4.5 kWh

Calculate the energy transferred to a 1 kW appliance over 30 minutes.

0.5 kWh

30 kWh

31 kWh

What does an electricity meter measure?

watt

joules

kilowatt-hours

Calculate the cost of electricity in pence for a particular household, if one unit costs 10 pence and 10 units have been used. 

1 penny

20 pence

100 pence

Calculate the cost of electricity in pounds for a particular household, if one unit costs 10 pence and 10 units have been used. 

1 pound

20 pounds

100 pounds

Calculate the cost of electricity in pounds for a particular household, if one unit costs 20 pence and 10 units have been used. 

1 pound

2 pounds

200 pounds

What is essential to do in order to save fuels and pay less for electricity?

Use less efficient appliances.

Use more efficient appliances.

Use old and outdated appliances.

  • Question 1

What type of energy is used by most appliances at home?

CORRECT ANSWER
electrical
EDDIE SAYS
Electrical energy is used by most appliances at home.
  • Question 2

What is the unit of the energy transferred to electrical appliances by mains electricity?

CORRECT ANSWER
kWh
EDDIE SAYS
The unit of electricity transferred to appliances is kilowatt-hour (kWh).
  • Question 3

Calculate the energy transferred to a 2 kW appliance over 3 hours.

CORRECT ANSWER
6 kWh
EDDIE SAYS
energy transferred = 2 kW x 3 h = 6 kWh
  • Question 4

Calculate the energy transferred to a 500 W appliance over 3 hours.

CORRECT ANSWER
1.5 kWh
EDDIE SAYS
energy transferred = 0.5 kW x 3 h = 1.5 kWh. If the power is given in W, you must divide by 1000 to get the kW, so your calculation is right.
  • Question 5

Calculate the energy transferred to a 1 kW appliance over 30 minutes.

CORRECT ANSWER
0.5 kWh
EDDIE SAYS
energy transferred = 1 kW x 0.5 h = 0.5 kWh. If the time is given in minutes, you must divide by 60 to get the time in hours, so your calculation is right.
  • Question 6

What does an electricity meter measure?

CORRECT ANSWER
kilowatt-hours
EDDIE SAYS
Electricity meters measure the units of electricity, which are kilowatt-hours.
  • Question 7

Calculate the cost of electricity in pence for a particular household, if one unit costs 10 pence and 10 units have been used. 

CORRECT ANSWER
100 pence
EDDIE SAYS
cost = number of units x cost per unit = 10 x 10 = 100 pence
  • Question 8

Calculate the cost of electricity in pounds for a particular household, if one unit costs 10 pence and 10 units have been used. 

CORRECT ANSWER
1 pound
EDDIE SAYS
cost = number of units x cost per unit = 10 x 10 = 100 pence = £1.00. Alternatively, one can convert pence into pounds before the calculation. Let's try that at the next question.
  • Question 9

Calculate the cost of electricity in pounds for a particular household, if one unit costs 20 pence and 10 units have been used. 

CORRECT ANSWER
2 pounds
EDDIE SAYS
cost = number of units x cost per unit = 10 x 0.2 = £2.00. There are 100 pence to a pound, so 20 pence would be 20/100 = £0.20 (0.2).
  • Question 10

What is essential to do in order to save fuels and pay less for electricity?

CORRECT ANSWER
Use more efficient appliances.
EDDIE SAYS
The use of more efficient appliances ensures that we do not waste fuels, we reduce pollution and we save money in electricity.
---- OR ----

Sign up for a £1 trial so you can track and measure your child's progress on this activity.

What is EdPlace?

We're your National Curriculum aligned online education content provider helping each child succeed in English, maths and science from year 1 to GCSE. With an EdPlace account you’ll be able to track and measure progress, helping each child achieve their best. We build confidence and attainment by personalising each child’s learning at a level that suits them.

Start your £1 trial

Start your trial for £1