Experiment 4 — Hit the Target with Light

Topic: Physics · Classes 6–7 · Light: reflection from a plane mirror

Aim: Bounce the torch beam off the mirror and hit the target on the wall.

Daily: A periscope, a dentist’s mirror, a cycle’s rear-view mirror and the mirror in your bathroom all obey the same law. Drivers see behind them because light reflects at a predictable angle.

Question: You turn a mirror by 10°. The reflected beam turns by…

Exp: Rotating the mirror changes both the incident and reflected angles, so the beam swings by twice the tilt.

Question: The law of reflection states that…

Exp: Both angles are measured from the normal.

Question: Why can you not see your face in a sheet of paper?

Exp: Diffuse reflection forms no image.

Exp: Two mirrors at 45° send light around a corner.

Question: Black surfaces look black because they…

Exp: Little light returns to your eye.