Knowing that the index of refraction of air is 1 and the index of refraction of
ID: 1459125 • Letter: K
Question
Knowing that the index of refraction of air is 1 and the index of refraction of water is 1.33, how many degrees will an anchor chain in the water appear to bend if it enters at an angle of 25 degrees from the perpendicular/normal?
What will be the speed of propagation of the light in m/s as it travels through the water?
Light enters the aperture of you’re AN/PVS-15 Night Vision Goggles at an incident angle of 32 degrees and refracts at an angle of 20.5 degrees from the perpendicular. What is the index of refraction of your objective lens?
What is the speed of propagation of the light in m/s as it passes through the lens?
Explanation / Answer
here,
n1 = 1
n2 = 1.33
theta1 = 25degree
let it seems theta2 from the normal
using snell's law
sin(theta2)/sin(theta1) = 1/1.33
theta2 = 18.53 degree
the anchor chain seems to bend at an angle of 6.47 degree
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speed of lightin water , v = C/n
v = 3 * 10^8 / 1.33
v = 2.56 * 10^8 m/s
the speed of light in water is 2.56 * 10^8 m/s
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theta1 = 32 degree
theta2 = 20.5 degree
using snell's law
n2/n1 = sin(theta1) /( sin(theta2))
n2 = sin(32) /sin(20.5)
n2 = 1.51
the refrative index of the objective lens is 1.51
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speed of light through the lens , v = C/n2
v = 3 * 10^8 / 1.51
v = 1.99 * 10^8 m/s
the speed of light in water is 1.99 * 10^8 m/s
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