Question

The radius of curvature of a plane mirror is:
A. zero
B. infinite
C. negative
D. finite

Answer 1

Hint: The radius of curvature of the curve at a particular point is defined as the radius of the approximating circle. Now Consider the plane mirror as a part of an infinitely large spherical surface.

Complete step by step answer:
As we know that the radius of curvature of a curve at a particular point is defined as the radius of the approximating circle at that point.
Now in the case of a plane mirror, we consider it as a part of an infinitely large spherical surface.
So, the radius of curvature for the plane mirror will be infinite.
Hence, the correct option is B, i.e., infinite.

Additional Information:
Characteristics of a virtual image formed by the plane mirror:
The image of a real object seen in the plane mirror is located where light reflects from the mirror to the eye of the observer seems to originate. The virtual image is behind the mirror and not at the surface of the mirror.
Image formed by a plane mirror is exactly the same distance behind the plane mirror as the object is in front of it. A virtual image is one from which light rays appear to originate, but they do not actually pass through the image.

Note: Students should understand the construction of a plane mirror as a part of the infinitely large spherical surface so that they can easily answer this question. Here radius of curvature cannot be zero for an infinitely large spherical surface, so option A is incorrect while the radius of curvature is negative for the concave mirror, not for plane mirror, so option C is incorrect and it is infinite, so option D is also incorrect.