Question

An under water swimmer is at a depth of 12 m below the surface of water. A bird is at a height of 18 m from the surface of water, directly above his eyes. For the swimmer the bird appears to be at a distance from the surface of water equal to : (Refractive index of water is 4/3)

• A. 12 m
• B. 9 m
• C. 18 m
• D. 24 m

Answer 1

Answer: (D)

$$\begin{array}{c}Accordingtoquestion................\\ Here,thebirdliesinAirmediumandobserveristheswimmerwhichliesinwater.\\ sothat,Refractiveindexofwater\left(\mu \right)=\frac{4}{3}\\ \mu =\frac{realheight}{apparentheight}\\ \frac{4}{3}=\frac{realdepth}{18}\\ realheight=\frac{4}{3}\times 18=24\\ realheight=24mabovethesurfaceofwater.\\ sothecorrectoptionisA.\end{array}$$