There is a small air bubble at the centre of a solid glass sphere of radius $r$ and refractive index $\mu .$ What will be the apparent distance of the bubble from the centre of the sphere, when viewed from outside?

• A

  r
• B

  $\frac{r}{\mu}$
• C

  $r\left(1-\frac{1}{\mu}\right)$
• Correct answer
  D

  Zero

Solution

' As the object is at centre of the sphere. $\therefore$ All rays will fall normally on surface, hence they do not deflect. Thus, a virtual image is formed at the centre $O$. $\therefore$ Apparent depth $=$ Real depth

Hence, the correct answer is option: 'D'.