A point object is placed at the centre of a glass sphere of radius 6cm and refractive index 1.5. The distance of virtual image from the surface is

Options

A. `2cm`
B. ` 4 cm`
C. `6 cm`
D. `12 cm`

Answer

C

Explanation

Using refractio formula `(._(1)mu_(2)-1)/(R)=(._(1)mu_(2))/(v)-(1)/(u)`
in given case, medium `(1)` in glass and `(2)` is air
So `(._(g)mu_(a)-1)/(R)=(._(g)mu_(a))/(v)-(1)/(u)implies((1)/(1.5)-1)/(-6)=(1)/(1.5v)-(1)/(-6)`
`=(1-1.5)/(-6)=(1)/(v)+(1.5)/(6)implies(0.5)/(6)=(1)/(v)+(1)/(4)`
`implies(1)/(v)=(1)/(12)-(1)/(4)=-(2)/(12)=-(1)/(6)implies6 cm.`