# Homework Help: Two wavelengths, max/min at same angle

1. Mar 23, 2009

### cashmoney805

1. The problem statement, all variables and given/known data
Light goes through two slits 40 mm apart. Does an angle exist at which light of wavelength 440nm has a maximum and light of wavelength 660nm has a minimum?

2. Relevant equations
dsin$$\theta$$=m$$\lambda$$1 = maximum
dsin$$\theta$$=(m+ 1/2)$$\lambda$$2 = minimum

3. The attempt at a solution
I solved for sin$$\theta$$ in each case, so I got:

m$$\lambda$$1 = (m+ 1/2)$$\lambda$$2

$$\lambda$$1 = 660nm
$$\lambda$$=440 nm

Now I'm stuck. Both Ms do not have to be the same, right? So do I have to solve for one of the Ms and stick it into an equation I listed in part 2 above? If so, that's a crazy calculation. Thanks!

2. Mar 23, 2009

### Redbelly98

Staff Emeritus
Correct, the m's can be different. But they must both be integers.

Are the slits really 40 mm apart? That's pretty far for an optical double slit setup.

3. Mar 23, 2009

### cashmoney805

They're actually 40 nm apart, sorry.

4. Mar 23, 2009

### Redbelly98

Staff Emeritus
Are you sure it's not 40 μm?

5. Mar 23, 2009

### cashmoney805

ah yes you're right