Question
Light from a point source in air falls on a spherical glass surface (refractive index, $\mu=1.5$ and radius of curvature $=50 \mathrm{~cm}$ ). The image is formed at a distance of 200 cm from the glass surface inside the glass. The magnitude of distance of the light source from the glass surface is __________ m.

Answer

4
Image
$\frac{\mu_{2}}{v}-\frac{\mu_{1}}{\mathrm{u}}=\frac{\mu_{2}-\mu_{1}}{\mathrm{R}}$
$\frac{1.5}{200}-\frac{1}{-\mathrm{x}}=\frac{1.5-1}{50}$
$\frac{1}{x}=\frac{1}{100}-\frac{3}{400}$
$\mathrm{x}=400 \mathrm{~cm}$
$\mathrm{x}=4 \mathrm{~m}$

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