Question

A point object is placed on the principle axis of a converging lens and its image $\left(I_1\right)$ is formed on its principle axis. If the lens is rotated by an small angle $\theta$ about its optical centre such that its principle axis also rotates by the same amount then the image $\left(I_2\right)$ of the same object is formed at point $P$. Choose the correct option.

• A. Point $P$ lies on the new principle axis.
• B. Point $P$ lies on the old principle axis.
• C. Point $P$ is anywhere between the two principle axes
• D. None of these

Answer 1

Answer: (C)

Point $P$ is anywhere between the two principle axes

$\begin{array}{c}{u}^{\prime }=u\cos \theta \\ \text{So}p\text{does not lie on new or old}\\ \text{principle axis it lies between two principle}\\ \text{axes}\\ \text{option}C\text{is correct}\end{array}$