Question

A plane mirror is made up of
A. Few meters thick glass plate
B. Few millimeters thick glass plate
C. Few centimeters m thick glass plate
D. None

Answer 1

Hint:Plane mirrors are usually the most commonly used mirrors in our day to day lives. These are generally confined to small widths. Low thickness of the mirror prevents distortion of the image.Mirrors are polished surfaces coated with mercury such that they reflect most of the light falling on them.

Complete answer:
A plane mirror is made of a glass plate that is several millimeters thick. One glass plate surface is polished to a high degree of smoothness that forms the front part of the mirror and the other (back) surface is silvered (i.e. painted with silver, mercury or some other material.)Hence, the required answer is a few millimeters thick glass plate.

The correct option is B.

Additional information:
Plane mirror: A plane mirror is a mirror that has a reflective (planar) flat surface. The angle of reflection equals the angle of incidence for light rays striking a plane mirror. The incidence angle is the angle between the incident ray and the normal surface area (an imaginary line perpendicular to the surface). The angle of reflection is thus the angle between the reflected ray and the normal, and a collimated beam of light, with the exception of diffraction effects, does not spread out from a plane mirror after reflection.

Note: They are used in periscopes, for signaling, in kaleidoscopes, to see dangerous circular curves, in meters, as mirror tiles, in overhead projectors, in SLRs, in car wing mirrors, in microscopes and to name only a few, as reflecting number plates. It is important to remember that the radius of curvature of a plane mirror is located at infinity.