The figure ,shows a transparent sphere of radius`R`and refractive index`mu`.An object `O`is placed at a distance `x` from the pole of the first surface so that a real image is formed at the pole of the exactly opposite surface.

If `x=2R`,then the value of `mu`is

Options

A. `1.5`
B. `2`
C. `3`
D. none of these

Answer

C

Explanation

`(mu_(2))/(v)-(mu_(1))/(u)=(mu_(2)-mu_(1))/(R ) rArr(mu)/(2R)-(1)/(-2R)=(mu-1)/(2R)`
`(mu)/(2R)=(mu-1)/(R )-(1)/(2R) rArr (mu)/(2R)=(2mu-2-1)/(2R)`
`mu=2 mu-3`
` mu=3`