A prism having an apex angle of $4°$ and refractive index of $1.50$ is located in front of a vertical plane mirror as shown. A horizontal ray of light is incident on the prism. The total angle through which the ray has deviated is:

A horizontal light ray passes through a prism $(\mu =1.5)$ of angle $4°$. Further, it is incident on a plane mirror $M,$ that has been placed vertically. By what angle the mirror is rotated so that the ray after reflection becomes horizontal?

An equilateral prism is kept on a horizontal surface. A typical ray of light $PQRS$ is shown in the figure. For minimum deviation