A point source is located 2.75 cm below the surface of a lake. The area of surface that transmits all the light that emerges from the surface is :

Question

A point source is located 2.75 cm below the surface of a lake. The area of surface that transmits all the light that emerges from the surface is : (A)  0.304 text m2  (B)  30.4 text m2  (C)  384 text m2  (D)  3.04 text m2

Tardigrade Admin · Accepted Answer

Now, using the relation r=(h/√μ 2-1) or A=π r2=(π h2/μ 2-1) =(3.14× (2.75)2/( (4)3 )2-1)=30.4m2

Q. A point source is located $2.75 c m$ below the surface of a lake. The area of surface that transmits all the light that emerges from the surface is :

$0.304 m^{2}$

$30.4 m^{2}$

$384 m^{2}$

$3.04 m^{2}$

Now, using the relation
$r = \frac{h}{μ ^{2} - 1}$
or $A = π r^{2} = \frac{π h ^{2}}{μ ^{2} - 1}$
$= \frac{3.14 \times ( 2.75 ) ^{2}}{( \frac{4}{3} ) ^{2} - 1} = 30.4 m^{2}$

Q. A point source is located 2.75cm below the surface of a lake. The area of surface that transmits all the light that emerges from the surface is :

0.304m2

30.4m2

384m2

3.04m2