Revise GCSE Physics

Question: What is a Thermogram?

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Thermograms are pictures produced by thermal cameras.

Remember: Thermograms show the Temperature of an object.

Thermal cameras detect only Infrared radiation, which we cannot see, and then produce a false colour image called a thermogram to enable us to visualise the IR profile of the object.

The hotter an object, the more IR infrared radiation it will be emitting. By detecting the intensity of IR radiation from each point on the object the camera can work out which parts are hotter and which are cooler, which is the related to their temperatures.

It is important to realise that the thermal camera does not see any visible light, and records no visible light. If the camera produced an exact image of what it actually 'saw' the image would be invisible to our eyes. The camera therefore creates an image for us using visible light to represent the temperature of the object in front of the camera. This is called a False Colour Image.

The different temperatures of an object viewed by a thermal camera are represented by a range of colours on the thermograms. To understand the thermogram we need to know what the colurs on a thermogram image actually mean.