Reflection of Light

When a ray of light is incident on a plane mirror, it undergoes reflection. Reflection is the process by which light waves bounce off a surface and change direction. In the case of a plane mirror, the incident ray and the reflected ray lie in the same plane, and the angle of incidence is equal to the angle of reflection.

Angle of Incidence and Angle of Reflection

The angle of incidence is the angle between the incident ray and the normal line drawn to the mirror surface at the point of incidence. The normal line is perpendicular to the mirror surface. The angle of reflection is the angle between the reflected ray and the normal line at the point of reflection.

Deviation of the Reflected Ray

When a ray of light is incident on a plane mirror at an angle, the reflected ray deviates through an angle. The deviation of the reflected ray can be explained using the concept of the law of reflection.

According to the law of reflection, the angle of incidence is equal to the angle of reflection. This means that the incident ray and the reflected ray make equal angles with the normal line. Since the normal line is perpendicular to the mirror surface, the incident ray and the reflected ray are symmetric about the normal line.

Explanation of Deviation

1. Incident Ray: The incident ray is the ray of light that is approaching the mirror surface. It makes an angle with the normal line.

2. Normal Line: The normal line is drawn perpendicular to the mirror surface at the point of incidence.

3. Reflected Ray: The reflected ray is the ray of light that bounces off the mirror surface. It makes an angle with the normal line.

4. Angle of Incidence: The angle of incidence is the angle between the incident ray and the normal line.

5. Angle of Reflection: The angle of reflection is the angle between the reflected ray and the normal line.

6. Deviation of the Reflected Ray: The deviation of the reflected ray occurs because the incident ray and the reflected ray are symmetric about the normal line. This means that the reflected ray does not continue in the same direction as the incident ray, but changes direction.

7. Equal Angles: The angles of incidence and reflection are equal. This ensures that the reflected ray retains the same angle with the normal line as the incident ray.

Conclusion

When a ray of light is incident on a plane mirror at an angle, the reflected ray deviates through an angle. This deviation is a result of the equal angles of incidence and reflection, as dictated by the law of reflection. The incident ray and the reflected ray are symmetric about the normal line, causing the reflected ray to change direction.

Deviation=(180-2i)deg where i=angle of incidence