Question

If two mirrors are kept at 60${}^\circ$to each other, then the number of images formed by them is
(A) 5
(B) 6
(C) 7
(D) 8

Answer 1

Hint: -
The mirrors that we are talking about are plane mirrors. A plane mirror forms a virtual image, which is of the same size as that of the object. The light rays after reflection form the image. Now, here we have placed two plane mirrors close to each other at some angle.

Complete step by step solution:
If more than one plane mirrors are placed closed to each other at some angle then the number of images formed is given by the formula $n=\dfrac{360{}^\circ }{\theta }-1$
Here $\theta$ is the angle between the two mirrors.
Putting $\theta$= $60{}^\circ \\\$,

$$n=\dfrac{360{}^\circ }{60}-1 \\\ =6-1 \\\ =5 \\\$$

So, the number of images formed are 5. Hence, the correct option is (A)

Additional Information:
If plane mirrors are adjoined at right angles to each other then it is called a right-angle mirror. Such a mirror can be found in a bathroom. There is a relationship between the size of the angles and the number of edges of the mirrors that are visible.

Note:
The angle is measured in degree, there is no need to convert into degree radians. The combination of such plane mirrors is also used in the kaleidoscope which forms a beautiful pattern. The size of the images produced by such a combination depends upon a number of factors such as distance of the object from the plane mirror. Plane mirror never forms a real image.