The radius of curvature of  a plane mirror is

Correct option is A

Correct Answer: A. ∞ (infinity)

• A plane mirror is a flat mirror with no curvature.
• The radius of curvature (R) is the radius of the sphere of which the mirror is a part.
• For a plane mirror, this radius is infinite because the mirror surface is flat, not curved.
• Hence, the radius of curvature R=∞.

Additional Information

• For concave or convex mirrors, radius of curvature is finite and related to focal length by:

R=2f

• Plane mirrors always form virtual, erect, and same size images.
• Their focal length is also considered infinite because f=R/2=∞/2=∞.