Question

Show, with a diagram, how an image is produced in a totally reflecting prism.

Show, by ray diagram, how a totally reflecting glass prism can be used to deviate a ray through 90°.

Answer 1

In a 45°-90°-45° prism, a ray entering normally through one shorter face hits the hypotenuse at 45°, exceeding the critical angle (~42°). Total internal reflection occurs, and the ray emerges normally from the opposite shorter face, turning through 90°. This prism reflects light without loss, forming a laterally inverted image, commonly used in periscopes to replace plane mirrors.