Required Practical 21: Radiation and Absorption

About this practical...

So simple yet so important. By watching what happens with Leslie?s cube, you get to see the variation of infrared heat given off from different colours. Most importantly, as the different colours are all getting their heat from the same place, it removes potential variation and makes the water temperature a control variable. This simple experiment is so fundamental, and it explains ideas from what colour clothes you should wear in which climate to why paramedics wrap patients in thin silver blankets.


1. Setup the selection of test tubes in a test tube rack

2. Add a thermometer into each test tube

3. Using a measuring cylinder, add the same amount of hot water to each (not boiling, less than 80°C)

4. Record the temperature of each thermometer

5. Record the temperature every 30 seconds and record it for approximately 10 minutes

6. Plot cooling curves and note the effects of different colour/texture has on the rate of cooling

It is very important to see the demonstration involving Lesley's cube to support your result analysis

Safety & Managing Risks

Usual lab rules must be followed: Bags and stools tucked away and notify the teacher of any spills or breakages immediately. Take care of the proximity of water to the sources of electricity. Do not use excessively hot water, your teacher will help you with this. For more detailed information, please consult CLEAPSS.

Technician notes:

Boiling tubes (each pair needs 1 painted silver, 1 painted matt black)

100 ml plastic measuring cylinders



Lesley's cubes (Teacher only)

Infrared thermometer (Teacher only)

This page was updated on: 8th January 2022