Here we're going to make a periscope which is a device for seeing over the top of things (No it's not like a stool)
|Big sheet of Cardboard or thin plastic (something you're able to cut with scissors).Alternatively to save yourself some time you could try and find a long square cardboard tube. Like a tall paper milk carton.|
|Two flat mirrors|
Okay, got the stuff? ... We’ll proceed then. Cut out your cardboard into four shapes like the ones below. Note the size of each compared to each other. This is important, that’s why we drew a grid, to make it a little more obvious. (The colours are not important it’s just there to help your know where each bit goes )
Right, now we’ve done that lets tape the shapes together into a tube like that shown below.
You can see, if you already had a cardboard tube how you can modify yours to look like the one below
Next step tape the mirrors onto the ends of the tube as shown, we should have pointed out that you need mirrors bigger than the end on your tube but then, we didn’t how big your tube was did we?
Look though one end with the other end held high
Things should appear as though you’re seeing them from higher up. You should be able to see over fences and walls now that you couldn’t before without the aid of a...er....tool.
If you’ve done the experiment ‘spotting your mate’ (or at least read it) you should be able to work it out for yourself! If not, well it's quite simple. The light coming into the top of the periscope is reflected down the tube towards the second one. This is then reflected out of the periscope by the second mirror and towards you. Therefore you see the light that has come from higher up. (sounds kinda biblical eh?).
It doesn’t matter how long you tube is or whether its square or round but you do need to have your mirrors at 45degrees to the tube in order for it to work. (more important for the bottom mirror else all you’ll be able to see is cardboard!)