Chapter 23, Problem 93RPP

To determine

The reason why peephole lens in a hotel door have an approximately $180°$ view.

a. The light moves straight through the lens into the eye.

b. Light from about $90°$ from the straight-ahead direction is refracted into the observer’s eye, if very close to the lens.

c. Light from about $90°$ from the straight-ahead direction is refracted into the observer’s eye, if looking at the lens from inside the room.

d. The outside hall is illuminated, so reflected light from the objects inside the $180°$ angle goes into the lens.

e. Both b and d.