Red light with a wavelength of 660 nm and blue light with a wavelength of 480 nm are beamed at a double slit with a separation of 2x10^-3 mm. The third order maximums for the different colours occur at different spots. What is the angle between the second order maximums?

I need help solvong this question. Would I need to use the formula nλ=dsin(theta)?

Question

Red light with a wavelength of 660 nm and blue light with a wavelength of 480 nm are beamed at a double slit with a separation of 2x10^-3 mm. The third order maximums for the different colours occur at different spots. What is the angle between the second order maximums? 

I need help solvong this question. Would I need to use the formula nλ=dsin(theta)?

festinger · Answer

Yes; apply that formula for the 2 colours with n=3 and solve for $\theta$. The difference in $\theta$ is the answer the question wants.

anonymous · Answer

thanks! So I got θ=41.3 and θ=28.7. I would take the difference and get 12.6 degrees right?

festinger · Answer

No, n should be 3, not 2. We are talking about third order maximums.