Correct Answer - Option 1 : 1/2
Concept:
Mirror:
- The optical instrument which reflects the light and forms the image of the object is called a mirror.
- The mirror has a spherically curved reflecting surface called a spherical mirror.
There are two types of spherical mirror:
-
Concave mirror: The spherical mirror having an inward reflecting surface is called a concave mirror.
- The images form by the concave mirror can be real as well as virtual.
-
Convex mirror: The mirror whose reflecting surface is outward is called a convex mirror.
- The images formed by the convex mirror are always virtual.
Explanation
- We know that if the radius of curvature of the spherical mirror is R, then the focal length (f) of the spherical mirror is given as,
\(\Rightarrow f = \frac{R}{2}\) ----(1)
- By equation 1 it is clear that the focal length of the spherical mirror depends on the radius of curvature.
So, the focal length of a spherical mirror is equal to ½ its radius of curvature.
