Explain why a ray of light passing through the centre of curvature of a concave mirror gets reflected along the same path.

A ray of light passing through the centre of curvature of a concave mirror is reflected back along the same path because it strikes the concave mirror at 90o (right angle) with the tangent at the point it strikes, due to which the incident ray coincides normal. Thus, the angle of incidence becomes 0o and angle of reflection also becomes 0o according to the law of reflection (∠i = ∠r).

Explanation

The reason for a ray of light passing through the centre of curvature of a concave mirror gets reflected back along the same path because the angle of incidence for a ray of light passing through the centre of curvature of a concave mirror is 0°, as it strikes the mirror normally or perpendicularly. At this point of contact, the incident light ray is perpendicular to the tangent making the incident ray and the reflected ray coincide with each other. 

This all happens because, the ray is coming from the centre of the sphere of which this curved mirror is the part, and in the case of a circle normal at a point always passes through the centre of the circle. 

Therefore the angle of incidence = 0o, and also the angle of reflection = 0o, (according to the law of reflection) $\angle i=\angle r=0$.

Thus ray of light retraces its path.

Tutorialspoint

Simply Easy Learning

Updated on: 10-Oct-2022

3K+ Views

Kickstart Your Career

Get certified by completing the course

Get Started