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Leslie’s Cube
AKA: Thermal Radiation Cube

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Fig 1: Leslie's Cube
Fig 1
Fig 2


A metal box with at least four different surfaces used to demonstrate radiant heat.


Leslie’s Cubes usually have four to six different surfaces/colours which radiate different levels of heat because of their individual properties. As a rule, if the surfaces are polished chrome, matt black, brushed chrome and dull metal, the matt black surface will radiate the most heat.

Some cubes must be filled with boiling water from a kettle and placed on a flat surface to ensure all sides are equally in contact with the water. Others can be placed on an electric hot-plate or on a tripod above a Bunsen burner. The two will differ in construction, so make sure you know which you have.

infra-red thermometers work best with this as they do not come into contact with the surfaces, thus eliminating conductive heating, though temperature sensors used in conjunction with dataloggers are regarded my many as being the best option.

Some Leslie’s Cubes come with a thermal sensor which normally needs to be connected to a multimeter to give results. The only problem with this approach is that the ‘temperature’ will be measured in volts and so may be confusing for pupils and teachers alike.

The Leslie’s Cube shows the effect of radiant heat so shouldn’t be confused with the conduction cross equipment which shows the effect of conductive heat.


 CautionThe can and its contents will remain hot for a long time after heating.

The contents of this page are for information only. Please refer to CLEAPSS or ASE safety advice and/or publications before undertaking any preparation, practical experiment or using any equipment featured on this site or any other.


Ensure that all water is expelled from the cube after use. Rust may appear over time where water is retained. Polish shiny surfaces regularly and repaint the matt finishes id necessary with heat resistant paints which are sometimes available through lab suppliers in spray cans.