question_answer

A small angle prism has a prism angle \[\left| A \right|=4{}^\circ \]and refractive index\[=1.5\]. It is placed with its base horizontal in front of a vertical mirror. A horizontal ray of light passes through the prism and is reflected back from the mirror. By what angle (in degree) the mirror should be rotated so that the reflected ray becomes horizontal?

Answer:

1.00