lesson
A mirror changes a light path
1 · Learn
Light can reflect from a surface. A smooth mirror reflects it in an organised way, which lets us see an image. A mirror does not need to make its own light.
Trace the route of light rather than assuming it can bend around a corner without interacting with anything. A simple periscope uses two suitably angled mirrors so reflected light can reach an eye along a changed route.
2 · Worked example
In a model periscope, I trace light from an object to the upper mirror, down to the lower mirror and then towards the viewing position. Each change of direction occurs at a mirror.
3 · Your turn
Why is an empty opaque tube with two bends not automatically a working periscope?
Check your answer
Light does not simply follow the bends. Appropriate reflecting surfaces are needed to direct it along the route.
4 · Apply your learning
Plan a periscope on paper with arrows at each reflection before an adult-led build using safe materials.
Adult guidance and safety
Use child-safe mirrors and no sharp glass. Do not point any viewing device at the Sun or a bright source.
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Check a calculation · Year 5 onward
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