Light Waves & Double-Slit Experiment Question .

[aehardin]

Light Waves & Double-Slit Experiment Question...

Our professor gave us an extra credit question on our last quiz & every single student got it wrong, all 150 of us! Anyways, here is the question, if you know the answer that would be greatly appreciated. Here is the question:

Describe in as much detail as possible the interference pattern that would
appear if one slit was illuminated with light of wavelength 400 nm and the
other slit was illuminated with light of wavelength 750 nm.

I thought that little if no interference would occur because the two lights are out of phase because they are incoherent sources, but I guess I was wrong! Help please...

 

[topsquark]

Our professor gave us an extra credit question on our last quiz & every single student got it wrong, all 150 of us! Anyways, here is the question, if you know the answer that would be greatly appreciated. Here is the question:

Describe in as much detail as possible the interference pattern that would
appear if one slit was illuminated with light of wavelength 400 nm and the
other slit was illuminated with light of wavelength 750 nm.

I thought that little if no interference would occur because the two lights are out of phase because they are incoherent sources, but I guess I was wrong! Help please...

I agree there will be no DOUBLE slit diffraction due to the different wavelenghts, but there IS such a thing as SINGLE slit diffraction.

-Dan

 

[kyle8921]

Hello,

First of all, it is not uncommon for all students to get a question wrong on a quiz. It is a learning opportunity and I'm glad you are seeking help to understand the concept better.

Now, onto the question. The double-slit experiment is a classic experiment in physics that demonstrates the wave nature of light. When a beam of light passes through two parallel slits, it creates a pattern of light and dark fringes on a screen placed behind the slits. This is known as an interference pattern.

In this case, we have two different wavelengths of light, 400 nm and 750 nm, illuminating the two slits. The wavelength of light determines the spacing between the fringes in the interference pattern. So, if one slit is illuminated with 400 nm light and the other with 750 nm light, the fringes will be spaced differently.

At the point where the two beams of light overlap, they will interfere with each other. This means that the peaks of one beam will overlap with the peaks of the other beam, creating a bright fringe. Similarly, the troughs of one beam will overlap with the troughs of the other beam, creating a dark fringe.

Since the two wavelengths are different, the spacing between the bright and dark fringes will also be different. This will result in a pattern of alternating bright and dark fringes, with the fringes becoming closer together as you move away from the center.

To summarize, the interference pattern in this scenario will consist of alternating bright and dark fringes, with the fringes becoming closer together as you move away from the center. This is due to the different wavelengths of light interfering with each other. I hope this helps you understand the concept better. Feel free to ask any further questions.