The index of refraction of a transparent liquid (similar to water but with a different index of refraction) is 1.28. A flashlight held under the transparent liquid shines out of the transparent liquid in a swimming pool. This beam of light exiting the surface of the transparent liquid makes an angle of theta a = 40 degree with respect to the vertical. At what angle (with respect to the vertical) is the flashlight being held under transparent liquid? Answer in units of degree. The flashlight is slowly turned away from the vertical direction. At what angle will the beam no longer be visible above the surface of the pool? Answer in units of degree.
Explanation / Answer
Data:Angle of incidence, w = ?Angle of refraction, a = 40 degRefractive index of water, nw = 1.28Refractive index of air, na = 1Solution:According to the Snell's law,nw * sin w = na * sin a1.28 * sin w = 1 * sin 40 sin w = 0.5022 w = 30.14 degAns:Angle of incidence in water, w = 30.14 deg