Question

A beaker is filled with water (n = 1.5) to a height h. Height of the beaker is 15 cm. When the bottom of the beaker is viewed vertically by an observer, the beaker appears to be half filled. Find the value of h.

Answer 1

Given:

Refractive index, n = 1.5

Height of the beaker = 15 cm

Apparent depth = `15/2` = 7.5 cm (since it appears half filled)

Formula:

n = `"Real depth"/"Apparent depth"`

Real depth (h) = n × Apparent depth

= 1.5 × 7.5

= 11.25 cm