JEE Advance - Physics (2025 - Paper 2 Online - No. 6)
Two identical concave mirrors each of focal length f are facing each other as shown in the schematic diagram. The focal length f is much larger than the size of the mirrors. A glass slab of thickness t and refractive index n_0 is kept equidistant from the mirrors and perpendicular to their common principal axis. A monochromatic point light source S is embedded at the center of the slab on the principal axis, as shown in the schematic diagram. For the image to be formed on S itself, which of the following distances between the two mirrors is/are correct:
Explanation
$$ \begin{aligned} & \frac{S-t}{2}+\frac{t}{2 n_0}=2 f \\ & S+t\left(\frac{1}{n_0}-1\right)=4 f \\ & S=4 f+\left(1-\frac{1}{n_0}\right) t \end{aligned} $$
Also
$$ \begin{aligned} & \frac{S-t}{2}+\frac{t}{2 n_0}=f \\ & S=2 f+\left(1-\frac{1}{n_0}\right) t \end{aligned} $$
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