Difference between Mirror and Lens

Lens and mirrors have a wide range of applications in our day to day life. People often confuse these two devices as they look similar but in reality, they are entirely different from each other in terms of functionality and performance. Let us see how mirror differs from the lens!

Mirror:

A mirror is a piece of glass that is polished from the outer surface or back. It reflects light that falls on its surface. It is made by polishing the outer surface of a glass. It has only one focal point as it has only one reflecting surface.

A mirror can be of three types, each type reflects light and produces images in a different way and thus the image of an object may appear larger, smaller, closer or more distant than actual size and distance of the object. The types of a mirror are as follows:

1) Plane mirror:

It is a flat mirror that reflects light rays in the same order as they fall on the mirror. In other words, the light is reflected at the same angle as the angle of incidence. The image in a plane mirror is reversed from left to right without top-bottom vertical reversal. The size and distance of the object are same in a plane-mirror reflection as it is in reality.

2) Concave mirror:

The convex mirror does not have a flat reflective surface its reflective surface curves inward and resembles the interior of a bowl. It is thicker at the edges than the center and produces upright and larger images.

3) Convex mirror:

It also does not have a flat reflective surface. Its reflective surface bends out or curves outwards like the outer surface of a bowl. It is thicker in the middle than at the edges. The Images of an object produced by convex mirror are upright and smaller than the object looks in reality.

Lens:

Lens is a transparent object that refracts light to create images that can be virtual or real. It can be of different types which are formed by combining flat, convex and concave surfaces. The two types of lens that we commonly use or see in our day to day life are as follows:

1) Convex lens:

The convex lens is thicker in the middle than the outside edges and its surface is curved outwards from the center. It converges light that travels through it into a single point. In other words, the parallel rays of light join at the same point after passing through the convex lens. The image produced by the convex lens depends on the distance and position of the object being viewed. It is used in binoculars, telescope, magnifier etc.

2) Concave Lens:

The concave lens is thicker on the edges than its middle portion and thus the rays which pass through the concave lens are diverted away from the focal point and only virtual and smaller images are produced. It is usually used in TV projectors.

Based on the above information, some of the key differences between mirror and lens are as follows:

MirrorLens
It is a piece of glass that is polished from the back or outer surface.It is a transparent piece of glass with a spherical surface.
It reflects the light that falls on its surface.It refracts the light. Convex lens converges and concave lens diverges the light.
It can be plane or spherical.It has two surfaces out of which one is curved inwards or outwards.
The working principle is the law of reflection.The working principle is the law of refraction.
It has only one focal point as it has only one reflecting surface.A lens has two focal points as it has two refracting surfaces.




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