Graph of position of image vs position of a point object from a convex lens is shown in the figure. The focal length of the lens is –

Step-by-step solution

2 f = 1 0 f = 5 cm 1 f = 1 v - 1 u df f 2 = dv v 2 + du u 2 df = f 2 dv v 2 + du u 2 u = 10, v = 10, du = 1 1 0 , dv = 1 1 0 (as there are 10 division in 1 cm scale, least count is 0.1 i.e., considered as error) So df = 2 5 1 1 0 1 0 2 + 1 1 0 1 0 2 = 2 5 2 1 0 × 1 0 0 df = 0.05 so f =(5.00 ± 0.05) cm.