Law of Reflection of Light

There are three laws of reflection. 

1. The angle of reflection is equal to the angle of incidence.
2. The incident ray, the reflected ray, and the normal lie in the same plane.
3. The incident ray and the reflected ray are on the opposite sides of the normal.

1. Aim: To verify that the angle of incidence is equal to the angle of reflection and to observe the laws of reflection.

2. Materials Required: mirror, drawing board, white paper, pins, protractor, scale, and pencil.

3. Procedure

• Fix the white paper on a drawing board.
• Draw a line PQ to represent the mirror's position. At point O on PQ, draw a perpendicular line ON (normal).
• Draw an incident ray AO making a 30° angle with ON.
• Place two pins (S and R) along the ray AO. Fix the mirror along PQ perpendicular to the board.
• Look for the reflected images of S and R in the mirror and align two pins (T and U) along the reflected ray.
• Remove the mirror and join T and U, extending it to O. Measure the angle ∠TON (angle of reflection).
• Repeat for angles of incidence 45° and 60° and record the corresponding reflection angles.

Verification of the laws of reflection

4. Observations: For each angle of incidence, the angle of reflection is equal to the angle of incidence.

5. Conclusion: The angle of incidence is always equal to the angle of reflection (∠i = ∠r). The incident ray, reflected ray, and normal lie in the same plane. This verifies the laws of reflection.