(a) Assuming that the critical angle of total reflection of light on the water surface is c and the radius of the transparent surface is r, then:

sinC= 1n，

So tanC= 1n2? 1?

According to the knowledge of mathematics, you must

? r=HtanC

Solution: r = HN2? 1

At other positions, the light is completely reflected and no light exits, so only one circular area can have light.

(b) (2) According to the fact that the frequency of light in the propagation process is constant and the speed of light in vacuum is C, the formula v=λν is obtained:

Relationship between refractive index and velocity: n=cV?

Concurrent availability: c=λ0ν

The wavelength of light in water is λ = λ=λ0n.

Answer: (a) Seen from above the water surface, only one circular area can have light, and the radius of the circle is Hn2? 1; The light at other positions is totally reflected, and no light exits;

(b) The wavelength of monochromatic light is λ0 in vacuum and λ 0n in water.