JEE PYQ: Ray Optics Question 20
Question 20 - 2020 (05 Sep Shift 1)
For a concave lens of focal length $f$, the relation between object and image distances $u$ and $v$, respectively, from its pole can best be represented by ($u = v$ is the reference line):
(1) [Graph 1]
(2) [Graph 2]
(3) [Graph 3]
(4) [Graph 4]
Show Answer
Answer: (4)
Solution
From lens formula, $\frac{1}{v} - \frac{1}{u} = \frac{1}{f}$ $\Rightarrow v = \frac{uf}{u + f}$ Case-I: If $v = u \Rightarrow f + u = f \Rightarrow u = 0$ Case-II: If $u = \infty$ then $v = f$. Hence, correct $u$ versus $v$ graph, that satisfies this condition is (a).
BETA
