The graph between object distance u and image distance v for a lens is given below. The focal length of the lens is

Step-by-step solution

From the lens formula: 1 f = 1 v - 1 u we have, 1 f = 1 10 - 1 -10 or f=+5 Further, u=0.1 and v=0.1 (from the graph) Now, differentiating the lens formula we have, f f^2 = v v^2 + u u^2 or f= ( v v^2 + u u^2 ) f^2 Substituting the values we have, f= ( 0.1 10^2 + 0.1 10^2 )(5)^2 f f=5 0.05