There is a small air bubble inside a glass sphere `(mu=1.5)` of radius 10 cm. The bubble is `4.0cm` below the surface and is viewd normally from the outside. Find the apparent dipth of the bubble.

Explanation

The observer sees the image formed due to refraction at the spherical surface when the light formt he bubble goes from the glass to the air.
Here, `u=-4.0cm, R=-10cm, mu=1.5` and `mu_(2)=1`.
`(1)/(v)+(-1.5)/(-4.0cm)=(1-1.5)/(-10cm)`
`(1)/(v)=(0.5)/(10cm)-(1.5)/(4.0cm)`
`v=-3.0cm` .
Thus, the bublle will appear `3.0 cm` below the surface.