JEE Main 2023 · 6 April · evening · Single correct · +4 / −1

A 2 meter long scale with least count of 0.2 cm is used to measure the locations of objects on an optical bench. While measuring the focal length of a convex lens, the object pin and the convex lens are placed at 80 cm mark and 1 m mark, respectively. The image of the object pin on the other side of lens coincides with image pin that is kept at 180 cm mark. The % error in the estimation of focal length is:

1. (a) 1.70
2. (b) 0.51
3. (c) 1.02
4. (d) 0.85