# Appliances and Power

In this worksheet, students will learn about energy transfer in appliances and will compare power ratings of appliances in watts (W).

Key stage:  KS 3

Curriculum topic:   Physics: Energy

Curriculum subtopic:   Calculation of Fuel Uses and Costs

Difficulty level:

### QUESTION 1 of 10

Many of the electrical appliances used at home transfer electrical energy into different forms of energy.

The energy that a machine uses each second is called its power. All appliances have a power rating in watts (W) or kilowatts (kW). The higher the power of the appliance, the more energy it uses. The amount of energy used by an appliance depends on its power and the time the appliance works for.

Electricity at home is sold by the kilowatt-hour. This is the energy used by a device running at 1000 W for 1 hour. The table below shows various electrical appliances and their power ratings.

 Appliance Power Rating (W) Electric cooker hob (one ring) 2000 Electric cooker oven 1500-2500 Microwave oven 600-900 Washing machine 2750 Vacuum cleaner 800-1200 Toaster 1200 Kettle 1200-2200 Hair dryer 1000 Plasma television 328 Fridge 110 Computer 78 Play Station 30 Energy efficient light bulb 15 Charging mobile phone 3

Use this information as we explore appliances and the energy they use.

How do all electrical appliances work at home?

They transfer electrical energy into different forms of energy.

They transfer various forms of energy into electrical energy.

They heat up water.

What do we call the energy that a machine uses each second?

Tick a unit of measurement for power.

Watt

Amp

Kilo

Tick another unit of measurement for power.

Hour

Volt

Kilowatt

Complete this sentence.

The ________ the power of the appliance, the more energy it uses.

lower

higher

less

Tick a factor that affects how much energy an appliance uses.

work

voltage

power

Tick another factor that affects how much energy an appliance uses.

energy cost

time it runs for

electric current

What unit is used to sell electricity at home?

kilogram

kilowatt-hour

kilojoule

What is the definition of 1 kilowatt-hour?

The energy used by an appliance running at 1000 kW for 1 hour.

The energy used by an appliance running at 1000 W for 10 hours.

The energy used by an appliance running at 1000 W for 1 hour.

List the appliances in order of energy used, from the one that uses the most energy to the one that uses the least energy.

## Column B

4
computer
5 (least)
energy-efficient light bulb
3
electric cooker oven
1 (most)
vacuum cleaner
2
washing machine
• Question 1

How do all electrical appliances work at home?

They transfer electrical energy into different forms of energy.
EDDIE SAYS
Electrical appliances transfer electrical energy into different forms of energy.
• Question 2

What do we call the energy that a machine uses each second?

power
EDDIE SAYS
The energy that a machine uses each second is called its power.
• Question 3

Tick a unit of measurement for power.

Watt
EDDIE SAYS
A unit of measurement for power is Watt.
• Question 4

Tick another unit of measurement for power.

Kilowatt
EDDIE SAYS
Another unit of measurement for power is kilowatt.
• Question 5

Complete this sentence.

The ________ the power of the appliance, the more energy it uses.

higher
EDDIE SAYS
The higher the power of the appliance, the more energy it uses.
• Question 6

Tick a factor that affects how much energy an appliance uses.

power
EDDIE SAYS
The power of an appliance affects the amount of energy it uses.
• Question 7

Tick another factor that affects how much energy an appliance uses.

time it runs for
EDDIE SAYS
The time an appliance runs for affects the amount of energy it uses.
• Question 8

What unit is used to sell electricity at home?

kilowatt-hour
EDDIE SAYS
Electricity at home is sold by the kilowatt-hour.
• Question 9

What is the definition of 1 kilowatt-hour?

The energy used by an appliance running at 1000 W for 1 hour.
EDDIE SAYS
A kilowatt-hour is the energy used by an appliance running at 1000 W for 1 hour.
• Question 10

List the appliances in order of energy used, from the one that uses the most energy to the one that uses the least energy.

## Column B

4
computer
5 (least)
energy-efficient light bulb
3
vacuum cleaner
1 (most)
washing machine
2
electric cooker oven
EDDIE SAYS
The correct order from the appliance that uses the most energy to the appliance that uses the least is: washing machine, electric cooker oven, vacuum cleaner, computer, energy-efficient light bulb.
---- OR ----

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