Question

A transparent glass tube 21cm long is filled with water.When viewed from top it appears 20%filled .what is the level of water in the tube.​

Answer 1

Answer:

Let it be filled to height 'h'cm. Then the part not in water is (21-h)cm.

So the apparent depth of the filled portion must be (21-h)cm.

apparent depth

real depth

=refractive index of water

21−h

h

=1.33

h=12cm

hence, 12cm water should be filled in a container.