Question

1. State the laws which help to find out the angle of incidence and angle of reflection in the ray diagram given above.
2. Find out the angle of incidence and angle of reflection in the given ray diagram.

Answer 1

(a) To determine the angles in the diagram, we use the laws of reflection:

1. First Law: The incident ray, the reflected ray, and the normal at the point of incidence all lie in the same plane.
2. Second Law: The angle of incidence (i) is always equal to the angle of reflection (r).

(b) In the diagram, the angle given (40°) is the angle between the incident ray and the reflecting surface (the glancing angle).

Angle of incidence (i): Since the normal is perpendicular (90°) to the surface, the angle of incidence is:

i = 90° − 40°

= 50°

Angle of Reflection (r): According to the second law of reflection, the angle of reflection is equal to the angle of incidence:

r = i

= 50°