Question

State the condition when a lens is called an equi-convex or equi-concave.
A. When radii of curvature of the two surfaces of the lens equal.
B. When height of the two lens are equal
C. When radii of curvature of the two surfaces of the lens are unequal.
D. None of the above.

Answer 1

Hint: In order to deal with this question, we will see the conditions required for a lens to be equi-convex or equi-concave. We will diagrammatically as well as theoretically see what are equi-convex and equi-concave lenses.

Complete Step-by-Step solution:

A lens is made up of two curved surfaces which can be concave or convex surfaces. We form an equi-convex or equi-concave lens having all the surfaces of the same kind and have the same focal length. The first and second main focus will be at the same distance from the optical center for such lenses.
Hence, the condition when a given lens is an equi-convex or equi-concave lens is: when radii of curvature of the two surfaces of lens equal
So, the correct answer is option A.

Note- Lenses are basically magnifying glasses with curved sides. A lens is a piece of clear glass that concentrates or disperses light rays when refracted by going through them. Lenses are used in telescopes and other magnifying instruments, regardless of the magnifying property. They are used for capturing the light rays in cameras. A lens type depends on how the light rays change when passing through the lens.