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Boiling kettle
Boiling kettle

Energy balance: boiling a kettle (optional lab exercise)


You should be able to perform this exercise in your kitchen using the equipment usually found there plus a small list of items you might need to buy - see the required apparatus pdf below. The only hazardous activity is boiling a kettle so please read the risk assessment for boiling a kettle below. To do this exercise download the lab instruction PDF at the bottom of the page. The exercise should take about an hour. The experiment is not a compulsory part of the course


To estimate the losses involved when boiling a kettle and hence find the kettle’s efficiency.


You may find the things you need lying round at home. If you do not have them to hand then we have provided links to purchase them online in the required apparatus document below. You can also find similar items in many other shops and online sales sites.

You will need:

• A measuring jug

• An electric kettle

• A plug-in power meter

• A digital kitchen probe thermometer

• A timer

• Cold water

Health and safety risk assessment

All of the lab exercises in this course are optional. Lab exercises aim to apply the theory already covered, enabling a deeper understanding of the material. This lab exercise involves working with water and a kettle. Below are the main risks associated with this lab exercise and measures to reduce these:

• Risk of kettle sides becoming very hot when boiled. Someone could touch the kettle and burn their hands. Kettle should have an insulated handle that does not heat up.

• Risk of hot water being split. The kettle must not be carried from kitchen when full of hot water. Extra care should be taken in pouring hot water into cups and, or pots. Cups or pots should be used to move hot water.

• Risk of slipping and falling on spilt water.

• Risk of children or other users pulling hot kettle onto themselves. Children must not be allowed to use the kettle. The kettle should only be used in the kitchen.

• Risk of damage to electric power cable. Check the full length of the cable plus the plug and sockets before plugging in the kettle.

• Risk of overflowing. Boiling water could land on people and scald them, or on socket causing electrocution. Maximum level must be clearly marked in the kettle

How did you do?

We want to know who has the most energy efficient kettle! Post your results in the comments section so we can find out.

Why not take photos of you carrying out your experiment and then post them to our media wall. You can also add a video to the media wall by uploading it to YouTube (or another social media site) and then cutting and pasting the embed code.

Remember to add your name and the experiment you are doing!

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This article is from the free online course:

Energy: Thermodynamics in Everyday Life

University of Liverpool