Question

A coin is placed at the bottom of a glass trough containing water µ=4/3 up to a height of 20cm.The depth it will appear when viewed from air:

Answer 1

Given :

Real depth of coin = 20 cm

Refractive index of water , µ = 4/3

 

To find :

The apparent depth of coin .

Solution :

Refractive index , µ = ( Real depth ) / ( Apparent depth )

now , µ of water = ( Real depth of the coin ) / ( Apparent depth of the coin )

=> 4/3 = 20 cm / Apparent depth of the coin

=> apparent depth of the coin = 20 * 3 / 4 cm

=> apparent depth of the coin = 15 cm

The apparent depth of coin is 15 cm .

Answer 2

Answer:

Let Real depth = x

Let Real depth = x∵ Refractive Index, μ = Real depth/Apparent depth

Let Real depth = x∵ Refractive Index, μ = Real depth/Apparent depth⇒ 4/3 = x/x – 4

Let Real depth = x∵ Refractive Index, μ = Real depth/Apparent depth⇒ 4/3 = x/x – 4⇒ 4x – 16 = 3x

∴ x = 16 cm.