Home/ Questions/Q 484726
Next
In Process
Jayshree Wable
Asked: 2022-11-10T10:05:00+05:30 In:

A jar of height h is filled wih a transparent liquid of refractive index `mu`, Fig. At the centre of the jar on the botom surface is a dot. Find the minimum diameter of a disc, such that when placed on the top surface symmetrically about the centre, the dot is invisible.
image.

A jar of height h is filled wih a transparent liquid of refractive index `mu`, Fig. At the centre of the jar on the botom surface is a dot. Find the minimum diameter of a disc, such that when placed on the top surface symmetrically about the centre, the dot is invisible.
image.
Parabola
Leave an answer

Leave an answer

Browse

1 Answer

  1. Let d be the diameter of the disc. The spot shall be invisible if the incident rays from the dot at O to the surface at d/2 at the criticale angle.
    Let `i` be the angle of inidence
    Using releatioship between refractive index and critical angle
    then, `” ” sint =(1)/(mu)` ltbr Unsing geometry and trigonometry
    Now `” ” (d//2)/(h)=tani`
    `rArr ” ” (d)/(2)=h tan i=h”[“sqrt(mu^(2)-1)”]”^(-1)`
    `:. ” ” d=(2h)/(sqrt(mu^(2)-1))`
    This is the required expression of d.

    • 0