Question

A mark placed on the surface of a sphere is viewed through glass from a position directly opposite. If the diameter of the sphere is $10\, cm$ and refractive index of glass is $1.5$. The position of the image will be

• A. $-20\,cm$
• B. $30\,cm$
• C. $40\,cm$
• D. $-10\,cm$

Answer 1

Answer: (A)

$-20\,cm$

Answer 2

Here, $\mu_{1} = 1, \mu_{2}=1.5$, $R = 5 \,cm, u = -10 \,cm$ $\frac{1.5}{10}+\frac{1}{v}= \frac{1-1.5}{-5} = \frac{1}{10}$or $\frac{1}{v}= \frac{1}{10}-\frac{3}{20} = \frac{-1}{20}$ $\Rightarrow v = -20 \,cm$