Question

what is difference between " a ray of light incident at an angle of 30 degree on mirror" and " a ray of light falls at an angle of 30 degree with a mirror" and " a ray of light is incident at an angle of 30 degree on a horizontal plane mirror"?​

Answer 1

1)Since, angle of incidence = angle of reflection = 30 degrees. The incident ray will have an angle of reflection of 30 degrees (made with a surface normal to the mirror surface). The reflected ray will make an angle of 60 degrees (90 - 30 degrees) with the mirror surface.

2)If the ray were not deviated, it would travel straight through the mirror. Due to the mirror, the incident ray is reflected at 30°. The ray travels 30° + 30° = 60°. The angle of deviation is 180° - 60° = 120°.