The correct answer is Curvature of the lens.
Important Points
- Focal length of a lens depends on its curvature and the medium outside the lens.
Additional Information
- The ability of a lens to converge or diverge light rays depends on its focal length.
- For example, a convex lens of short focal length bends the light rays through large angles, by focussing them closer to the optical centre.
- Similarly, the concave lens of a very short focal length causes a higher divergence than the one with a longer focal length.
- The degree of convergence or divergence of light rays achieved by a lens is expressed in terms of its power.
- The power of a lens is defined as the reciprocal of its focal length.
