Periscope
Use mirrors and paper to build your own periscope and see over walls!
This activity may be Fiddly
Use mirrors and paper to build your own periscope and see over walls!
This activity may be Fiddly
What will I need?
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How much taller can you make your periscope before you stop seeing the reflection?
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Shine a torch into the periscope’s eyepiece and place the other end next to a wall. What do you see?
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Can you make a periscope with three or more mirrors?
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What can you see when you look through your periscope?
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Describe what you think is happening when you look through the periscope.
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Where else do we use mirrors to help us see things we otherwise wouldn’t be able to?
A periscope allows us to see things that are otherwise out of sight. We see an object when light coming from it enters our eyes. The light may have been made by the object itself, or it may have simply bounced off it. Either way, the light travels in straight lines – so normally you have to look straight at something to see it. But when light hits a mirror, it bounces off – at the same angle it hits. Light travelling horizontally meets the first mirror in the periscope at 45 degrees, and bounces off at 45 degrees, making 90 degrees altogether – so it ends up travelling vertically downwards.
Mirrors allow you to see things that aren’t in your direct field of view. A rear-view mirror in a car, for example, reflects light coming from behind the driver into their eyes so that they can see cars and other objects behind them. And at the hairdresser’s a combination of two mirrors allows you to see the back of your head.