# 1-D wave interference

1. Mar 18, 2009

### XJellieBX

1. The problem statement, all variables and given/known data
Monochromatic light of wavelength $$\lambda$$ = 400 nm enters at A. It impinges on a ‘half-silvered mirror’ B, which directs some of the light to mirror C, while passing the rest to mirror D. Some of the reflected light from mirror C passes back through the half-silvered mirror, where it combines with reflected light from D, arriving at the detector. Mirror C is attached to a micrometer, so that it can be moved to change the path length B − C − B.
If mirror C is moved through 10 microns (1 micron is 10−6 m), how many maxima will be
observed at the detector? Assume that the intensity at D is intially a minimum.

2. Relevant equations
D(x,t)=asin(kx-wt+$$\phi_{0}$$

3. The attempt at a solution
I'm actually not sure how to approach this to begin with, so any advice is appreciated. I've also attached a copy of the diagram. I'm thinking this might have something to do with the path length being x1 and x2

#### Attached Files:

• ###### interferometer.jpg
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2. Mar 19, 2009

### tiny-tim

Hi XJellieBX!

If mirror C is moved through 10−6 m, how much longer does that make the path?

So how many wavelengths is that? And how many maxima will go past?

3. Mar 19, 2009

### XJellieBX

So if I find how many wavelengths that is, which i did find, i can figure out the number of maxima. I'm just not too sure if that is all this question is asking for, but thank you nevertheless =)