What will be the angle of incidence for a ray of light incident along the principal axis of a convex mirror?

Correct option is A

Sol: The correct answer is (a) 0°

Key points:

When a ray of light is incident along the principal axis of a convex mirror, it travels parallel to the principal axis. In this specific case, the angle of incidence is measured relative to the normal to the surface at the point of incidence

For a ray traveling along the principal axis, the normal at the point of incidence is also along the principal axis. Therefore, the angle of incidence is:

$$\theta_i$$ = 0°

This means that the ray strikes the mirror perpendicular to the surface, resulting in an angle of incidence of 0 degrees. Consequently, the reflected ray will follow the same path back along the principal axis.

Information booster:

Principal axis-

• The principal axis is the line that passes through the center of curvature of a reflecting surface, such as a mirror or lens.
• Light rays that are parallel to the principal axis will reflect or refract in such a way that they intersect at the focal point of the surface.
• The angle of incidence of a light ray with respect to the principal axis is equal to the angle of reflection, as described by the law of reflection.
• The focal length of a curved surface is the distance from the surface to the focal point, and it is determined by the curvature of the surface and the refractive index of the material.
• The principal axis is a key concept in understanding the formation of images by mirrors and lenses, as it determines the path of light rays and the location of the focal point