Question

A fish looking up through the water sees the outside world contained in circular horizon. If the R.I. of water 4/3 and the fish is 12 cm below the surface, the radius of this circle in cm is -

• A. 36$\sqrt { 7 }$
• B. $\frac { 36 } { \sqrt { 7 } }$
• C. $36 \sqrt { 5 }$
• D. $4 \sqrt { 5 }$

Answer 1

Answer: (B)

$\frac { 36 } { \sqrt { 7 } }$

Answer 2

r = $\frac { 12 } { \sqrt { \left( \frac { 4 } { 3 } \right) ^ { 2 } - 1 } }$ = $\frac { 36 } { \sqrt { 7 } }$ cm.