In the diving pool in the Richards Building, there is a glass window under the w
ID: 3892939 • Letter: I
Question
In the diving pool in the Richards Building, there is a glass window under the water.
There is a room full of air on the other side of the glass window pane. If I dive under the
water and look at the window, I notice that I can see the room on the other side of the
window only through a circular area. Outside that circle, light undergoes total internal
reflection at the surface between the glass and the air, and the window appears like a
mirror. If I am 1.34 m from the window, find the radius of the circle.
The index of refraction of water is 1.33, and the index of refraction of glass is 1.52. Be sure to
take into account that the light ray which is refracted at the glass-air surface is also
refracted at the glass-water surface and changes direction there too.
Explanation / Answer
index of refraction for glass water interface is 1.14. For the two surface refraction, resultant refractive index is
1.52 x 0.875= 1.33
HEnce critical angle= sin-1(1/1.33)= 48.75
tan c= h/1.34
Hence h= 1.527m is the radius of the circle.