Question

State which surface of a plane mirror reflects most of the light incident on it: the front smooth surface of the back silvered surface?
A. Back silvered surface
B. Front smooth surface
C. Both refract equally
D. Both reflect no light

Answer 1

Hint:There are two sides of a plane mirror, a smooth surface on the front and a silvered surface on its back. A surface reflects the most when it is cleanly polished. If a light is incident on a metal, it is reflected the most when the light is not absorbed or transmitted by the metal. Silver is a metal which absorbs the least amount of light.

Complete answer:
There are three types of mirrors, namely convex mirror, concave mirror and plane mirror. All of these three mirrors have a silvered surface and a smooth surface. Plane mirror is a straight mirror with a silvered surface in its back. If a spherical mirror has a curved surface which is silvered on its back side, then the mirror is called a concave mirror. If a spherical mirror has a curved surface which is silvered on its front side, then the mirror is called a convex mirror.Plane mirror has a flat surface which is reflecting.

Plane mirror produces a virtual and erect image on the opposite side of the plane. Now a silvered surface is used in a mirror because silver is one of the metal which reflects the most light which is incident on it. Hence polished silver is used in a mirror because of its ability to reflect the maximum light incident on it without absorbing it. Thus here, the back silvered surfaced surface reflects more light than a front smooth surface in a plane mirror.

Hence option A is the correct one.

Note: Apart from silver, another metal which is used and is less costly to use in a mirror is aluminum. These metals reflect light because light is an electromagnetic wave and when it is incident on these metals, the metal cancels the electric field of the light which is parallel to the mirror and hence gets reflected away.