Question

If center of curvature is =20 then f=what

Answer 1

as we know f=2f
So the focal length is =20/2=10
Thats it

Answer 2

Step-by-step explanation:

centre of curvature is also known as radius of curvature and focus is also known as focal length.

radius of curvature / centre of curvature is twice the focal length ( C = 2F ).

given that is centre of curvature is 20,

= 20 = 2F or 2F = 20,

= F = 20/2

therefore, F = 10 Ans.

Verify:

C = 2F

20 = 2 × 10

20 = 20 or L.H.S = R.H.S

Hence, verified.