KVPY SA Exam 2011 Question Paper

Question : 69 of 80

Marks: +1, -0

A student sees the top edge and the bottom center C of a pool simultaneously from an angle θ above the horizontal as shown in the figure. The refractive index of water which fills up to the top edge of the pool is

4/3

. If

h/x = 7/4

then cos θ is

$2/7$
$8/{3√45}$
$8/{3√53}$
$8/21$

Validate

Solution:

1 × \sin i = µ \sin r

\sin(90-θ)=4/3\sin r

\tan r=x/{2h}=4/{7×2}=2/7

\sin r=2/√53

\cosθ=4/3×2/√53=8/{3√53}

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