Question

When light from a point source in air falls on a spherical glass surface with refractive index $1.5$, an image is formed at a distance of $100cm$ from the glass surface. The distance of the light source from the glass surface is $100cm$. The radius of curvature is:

• A. $20cm$
• B. $40cm$
• C. $30cm$
• D. $50cm$

Answer 1

The correct option is A $20cm$

From the relation:

$\frac{{\mu }_2}{v}+\frac{{\mu }_1}{u}=\frac{{\mu }_2-{\mu }_1}{R}$,

we get: $\frac{1.5}{100}+\frac{1}{100}=\frac{1.5-1}{R}$

or, $R=20cm$