Question

Which of the following is the correct statement
a. The distance between the optical centre and the focus of the lens is called as focal length
b. The distance between the centre of curvature of the first lens and the second lens is called as focal length
c. The distance between the centre of curvature and the optical length is called as focal length
d. The distance between F and 2F is called as focal length​

Answer 1

Answer:

a) The distance between the optical centre and the focus of lens is called as focal length