This is one of a set of resources developed to support the teaching of the primary national curriculum. They are designed to support the delivery of key topics within science, design and technology, and maths (in this case, mainly science). This resource focusses on the investigation of how the light from a torch (flashlight) changes with distance.
Light is a type of electromagnetic radiation. Visible light is the range of the electromagnetic spectrum that can be seen with a human eye. The brightness, or intensity, of light is typically measured as the power per unit area.
The lamp in a torch produces light when it is supplied with electricity. This light from a lamp would normally extend out in every direction, so a torch typically uses reflective materials, such as the inside of a silvered cone, to aim it where it is desired. However, this focus is rarely perfect, and the light spreads out as the distance from the lamp increases.
In this activity learners will carry out an experiment to measure how the light from a torch changes with the distance from the lamp. They will record their results in a table and plot a graph.