Cardboard Periscope
Two angled mirrors let you peek over walls and around corners — the same trick submarines use.
Start building ↓The build
Cut the holes
Make a viewing hole near each end on opposite sides.
Mount mirror one
Fix a mirror at 45° behind the top hole.
Mount mirror two
Fix the second mirror at 45° behind the bottom hole, parallel to the first.
Look through
Light bounces top to bottom so you see over obstacles.
Each mirror reflects light at 45°, redirecting an incoming horizontal ray down the tube and out to your eye.
A closer look
The law of reflection (angle in = angle out) lets two parallel mirrors shift the line of sight without distorting the image.
Variables to test
- 1 Angle the mirrors slightly off 45° — how does the image shift?
- 2 Lengthen the tube; can you still see clearly?
More Physics
Homopolar Motor
A single AA battery, a magnet and a copper-wire loop spin into the simplest electric motor that actually works.
Switchable Electromagnet
Coil insulated wire around an iron bolt and a battery turns it into a magnet you can switch on, off, and strengthen at will.
Pendulum Timer
A swinging mass keeps remarkably steady time — build one and discover what really sets its rhythm.