Question

In the displacement method, a concave lens is placed in between an object and a screen. If the magnification in the two positions are m₁ and m₂ (m₁ > m₂), and the distance between the two positions of the lens is x, the focal length of the lens is
(a) $\frac{x}{m_{1}+m_{2}}$
(b) $\frac{x}{m_{1}-m_{2}}$
(c) $\frac{x}{(m_{1}+m_{2})^{2}}$
(d) $\frac{x}{(m_{1}-m_{2})^{2}}$

Answer 1

$<b>$

Option A is Correct

Answer 2

$\frac{x}{m_{1}+m_{2}}$ is distance between the two positions of the lens is x, the focal length of the lens.