Question

110. A fish 12 cm long is 5 cm under the water level.
Its length when viewed vertically above will be
(a) 12 cm
(b) 7 cm
(c) 5 cm
(d) none of these
​

Answer 1

Answer :

Length of fish = 12 cm

Real depth of fish = 5 cm

We have to find apparent depth of the fish$.$

★ Apparent depth in a medium is the depth of an object in a denser medium as seen from the rarer medium.

• Its value is smaller than the real depth.

Apparent depth can be calculated by using this formula :

• n = Dr/Da

→ n denotes refractive index of denser medium wrt rarer medium

→ Dr denotes real depth

→ Da denotes apparent depth

By substituting the values, we get

➠ n = Dr/Da

➠ 4/3 = 5/Da

➠ Da = 5 × 3/4

➠ Da = 3.75 cm

∴ (D) is the correct answer!