Question

15. In a vessel of depth H, upto what height a liquid of refractive index \frac{3}{2} should be filled so that now it appears to be half filled if viewed from top? (1) \frac{3H}{7} (3) \frac{2H}{5} (2) \frac{3H}{5} (4) \frac{4H}{7}​

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 depthreal depth=refractive index of water  

 21−hh=1.33

h=12cm

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