Question

Which one of the following is the best reflector of light?
A.Wood
B.Pencil
C.Wall
D.Plane mirror

Answer 1

Hint: Try and think of what would distinguish a material as a good reflector. In other words, if you were to hold a piece of wood, or a pencil, or mirror in front of you or stand in front of a wall, where would you most likely see your image?

Complete answer:
We know that reflection of light occurs when a light approaches a smooth polished surface and the light ray bounces back. The incident light ray that lands upon the surface is said to be reflected off the surface. The ray that gets bounced off is called the reflected ray.
There are different types of reflection of light:
1.Regular (Specular) Reflection: This refers to a clear reflection resulting in sharp, unidirectional reflected rays, with no haziness or blurriness. This occurs when the surface of the reflector is uniform and the reflector material is shiny, clear and polished
2.Diffused Reflection: This refers to reflection that entails a loss in the brightness and quality of reflection owing to rough uneven surfaces where light rays get reflected off in slightly different directions. This type of reflection helps us to see non-shiny objects.
3.No reflection: This refers to the situation where none of the incident light rays are reflected but all of them are scattered instead. This occurs when the surface of the reflector is rough and opaque.
From the options given to us, we can deduce that wood, pencil and walls are opaque surfaces and are most often rough and hence scatter off all the light incident on them, whereas a plane mirror is a smooth glass, uniformly coated with highly reflective material like silver or aluminium and polished.
Thus, a plane mirror seems to be the best reflector of light.

The correct option would be: D. Plane mirror.

Note:
Note that the plane mirrors remain good reflecting surfaces only as long as their surface remains uncontaminated by tarnishing or oxidation, and safe from impact.
Also, remember that it is not just the reflecting material that makes for a good reflection but also the consistency of the incident and reflected rays with the laws of reflection which state that:
1.The incident ray, the reflected ray, and the normal to the surface of the plane mirror must all lie in the same plane.
2.The angle of incidence = the angle of reflection.