JEE Main · 2026 · 24 Jan 2026 · Shift 2 · Geometrical Optics

A lens of power $+5$ D has focal length $f=\frac{1}{5}\text{m}=20$ cm, so every valid pair of object and image distances must satisfy $\frac{1}{v}+\frac{1}{u}=\frac{1}{20}$ (magnitudes). The readings $P_1(25,96)$, $P_2(30,62)$, $P_4(45,35)$ and $P_5(50,32)$ each return $\frac{1}{u}+\frac{1}{v}\approx \frac{1}{20}$ within reading error. For $P_3(35,37)$ an object at $35$ cm lies between $f$ and $2f$, so the image must form beyond $2f=40$ cm; the recorded $37$ cm instead gives $\frac{1}{35}+\frac{1}{37}\approx \frac{1}{18}$ cm${}^{-1}$, inconsistent with $f=20$ cm. The reading recorded by $P_3$ is incorrect.