The formula for the angle of deviation in the case of a plane mirror is $\delta =$ ${}^{\circ }-\left(2i+g\right)$ where $i$ is the angle of incidence and $g$ is the glancing angle.

When two plane mirrors are inclined at an angle ${60}^{\circ }$ with each other, the number of images formed of an object placed symmetrically between them will be_____.

When two plane mirrors are at a right angle with each other, the number of images viewed is _____.

_____ invented the periscope.

Reflecting periscopes can be constructed by _____ mirrors.

The phenomenon of _____ is used in a reflecting telescope.

What is an optical medium? Explain the types in it with two examples based on the amount of light they allow through them.

Write the construction of the pinhole camera.