Question

To find the focal length of a concave lens by plotting graphs between u and v or between 1/u and 1/v

Answer 1

Aim
To find, the focal length of a convex lens by plotting graphs between u and v or between 1/u and 1/v.

Apparatus
An optical bench with three uprights (central upright fixed, two outer uprights with lateral movement), a convex lens with lens holder, two optical needles, (one thin, one thick) a knitting needle and a half metre scale.

Theory
The relation between u, v and f for a convex lens is
to-find-the-focal-length-of-a-convex-lens-by-plotting-graphs-between-u-and-v-or-between-1u-and-1v-1
where,
f = focal length of convex lens
u = distance of object needle from optical centre of the lens
v = distance of image needle from optical centre of the lens.
Note. According to sign-convention, u has negative value and v has positive value. Hence, f comes positive.

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