Question

A converging beam of solar rays is incident on a concave spherical mirror whose radius of curvature is 0.8 m. Determine the position of the point on the optical axis of the mirror where the reflected rays intersect, if the extensions of the incident rays intersect the optical axis 40 cm from the mirror's pole.

Answer 1

The incident rays appear to converge $40cm$ behind the mirror and hence , $u=40cm$

$f=\frac{-R}{2}=-40cm$ negative sign since it is a concave mirror.

$\frac{1}{v}+\frac{1}{u}=\frac{1}{f}$

$⟹v=\frac{uf}{u-f}=\frac{-40\times 40}{40+40}$

$⟹v=-20cm$

Hence, reflected rays will meet at $20cm$ in front of mirror.