Question

A mark is made at the bottom of the beaker and a microscope is focused on it. the microscope is raised through 1.5 cm. to what height must the water be poured to bring the mark into the focus

Answer 1

The height must the water be poured to bring the mark into the focus is 6 cm.

Given:

Raise of microscope = d = 1.5 cm

Explanation:

Let the height of the water poured in the beaker be 't'

The apparent shift is given by the formula:

d = t × (1 - 1/μ)

Where,

μ = Refractive index of the medium.

Here, the medium is water.

The refractive index of water = 4/3

On substituting the values, we get,

1.5 = t × (1 - 1/(4/3))

1.5 = t × (1 - 3/4)

1.5 = t × ((4 - 3)/4)

1.5 = t × 1/4

t = 1.5 × 4

∴ t = 6 cm