# Homework Help: Fizeau experiment problem,

1. Sep 16, 2008

### jianxu

fizeau experiment problem, urgent

1. The problem statement, all variables and given/known data
A beam of monochromatic light, whose wavelength in free space is lambda, is split into two separate beams and each is then passed through identical troughs of water. The speed of light in a medium is given my v = c/n, where n is the refractive index of the medium. now the water in one of the troughs is stationary but moving in the other with speed v= 10 m/s << c(much less than c) in the direction of the light eam. Show that the phase difference between the merging beams is ((2 * pi * L )/ lambda)*(n^2 -1)*(v/c) where L is the length of the troughs. Suggest a suitable value for L in an experimental arrangement to test this result. Binomial expansion (1+x)^-1 approximately 1-x

2. Relevant equations
A * sin( 2*pi*f*t + phase difference)
f = frequency = v/lambda
t = elapsed time
V = c/n + v (1 - (1/(n^2)))
L = v*t
length contraction

3. The attempt at a solution

I've written down some of the equations I might need to solve this problem(wave equations, conversion equations, etc)

If I assume the observer viewing this is stationary, what I did was substitute some equations into the wave equation to try and achieve the above phase difference. wave equation is

and that's kind of as far as I got. Any advice would be great, thanks