Question

(a) Describe the image formation in a plane mirror.
(b) Give characteristics of image formation by a plane mirror.

Accepted Answer

(a) When a ray of light falls on a surface, then it can undergo one of the following three phenomena reflection, refraction, or absorption. When it falls on a normal surface most of the light gets absorbed. So mirrors are polished surfaces coated with mercury such that they reflect most of the light falling on them. Now based on the type of reflecting surface we can classify mirrors as concave, convex, or plane mirrors. Here we will be talking about the plane mirror only. So to form an image we require at least two rays from the object which meet or appear to meet at a point. In the case of a plane mirror, here we have used three images for better clarity in the ray diagram shown below.
For the ray starting from point A and travelling in a horizontal direction towards point E, the angle of incidence is zero, and hence it retraces its path. Similarly, the ray starting from A and travelling towards point C follows the law of reflection. When these rays are produced backwards they appear to meet at a point E and D. Now this image is known as a virtual image.
(b) Characteristics of image formation:

(i) The image formed by a plane mirror is virtual, erect, and laterally inverted.

(ii) The size of the image is equal to the size of the object.

(iii) The image distance behind the mirror is equal to the distance of the object in front of the mirror.

(iv) If an object is placed between two plane mirrors inclined at an angle $θ$ , then the number of images $n$ , formed are given in the following cases:

(a) If $\frac{360}{θ}$ is even, then $n = (\frac{360}{θ} - 1)$ for objects placed symmetrically or unsymmetrically.

(b) If $\frac{360}{θ}$ is odd, then $n = (\frac{360}{θ} - 1)$ for objects placed symmetrically.

(c) If $\frac{360}{θ}$ is odd, then $(n = \frac{360}{θ})$ for objects placed unsymmetrically.

(a) Describe the image formation in a plane mirror.
(b) Give characteristics of image formation by a plane mirror.

Important Questions on Light

Learn and Prepare for any exam you want !

(a) Describe the image formation in a plane mirror. (b) Give characteristics of image formation by a plane mirror.

Important Questions on Light

Learn and Prepare for any exam you want !

(a) Describe the image formation in a plane mirror.
(b) Give characteristics of image formation by a plane mirror.