Today we created a periscope, learning about how light is reflected at a specific angle. In this activity, carefully placed mirrors change the path light takes twice, making it possible to look over walls, around corners and even behind us – all without being seen. Submarines have periscopes so that people inside can what is on the surface of the water. A periscope is a useful example of the law of reflection at work. In a periscope, light from an object strikes the top mirror at 45° and bounces off at the same angle. This sends light directly down the tube and onto the lower mirror. This mirror, also at a 45° angle, reflects light directly to your eye.