Question

Class 10 physics project.

1. Determine the focal length of a convex lens by using two pins and formula f = uv/(u+v)

2. Determine the focal length of a convex lens by (a) the distant object method and (b) using a needle and a plane mirror.​

Answer 1

The object distance u, image distance v and the focal length f for a spherical mirror are related by the mirror formula

1- 1- 1-

v + u = f,

and for the spherical lens are related by the lens formula

1 1 1

--- --= -.

v u f