Question

The wavelength of red light from $He-Ne$ laser is $633nm$ in air but $474$ nm in the aqueous humor inside the eye ball. Then the speed of red light through the aqueous humor is

• A. $3\times {10}^{8}m/s$
• B. $1.34\times {10}^{8}m/s$
• C. $2.25\times {10}^{8}m/s$
• D. $2.5\times {10}^{8}m/s$
• E. $2.75\times {10}^{8}m/s$

Answer 1

Answer: (C)

$\frac{Speedoflightinair}{Speedoflightinaqueoushumor}$
$=\frac{Wavelengthoflightinair}{Wavelengthoflightinaqueoushumor}$
$\Rightarrow$ $\frac{v_1}{v_2}=\frac{{\lambda }_1}{{\lambda }_2}$ Or
$v_2=\frac{{\lambda }_2}{{\lambda }_1}\times v_1=\frac{474}{633}\times 3\times {10}^8$
$=2.25\times {10}^{8}m/s$