# Interference using white light

• songoku
In summary, the conversation discusses the use of white light in Young's double slit experiment and the resulting interference pattern. It is noted that the different wavelengths of light in white light will cause the colors to appear in different locations on the screen. There is also a mention of the possibility of additional colors appearing due to the combination of the seven colors in white light. The importance of conducting experiments to gain a better understanding of theory is also emphasized.

## Homework Statement

What will happen if we use white light at young's double slit experiment?

interference

## The Attempt at a Solution

Will we observe several colors on the screen because white light is composed from several light with different wavelengths?

Thanks

I wonder if the "several colors" will appear in the same places on the screen? Or will they be separated? Do you have a formula for the location as a function of the wavelength?

Hi delphi51

I guess the formula is d sin θ = n λ. Because the wavelengths are different for the colors composing the white light, θ will be different for each colors. But there is possibility that some colors fall on the same spot on the screen, for example maybe the 3rd order of red light and 5th order of yellow light.

So, the pattern obtained on the screen is seven colors composing white light and another several colors resulting from combination of some of the seven colors. And I think the interference pattern will not be a complete destructive or constructive interference since the waves have are not coherent.

Do I get it right?

Thanks

Looks good! Some would use the word "rainbow".
Next step: try it and see how good your prediction is!

Delphi51 said:
Looks good! Some would use the word "rainbow".
Next step: try it and see how good your prediction is!

Try it? You mean I do experiment? But I don't have any tools and I don't think the school will let me use the lab for now. So for now I just believe that my prediction is 99.99% accurate

Thanks

You'll miss out on the very important idea that theory depends on experiment, a real feeling for what the theory means, and the fun of it! A decent double slit is quite difficult to make and makes a pitiful interference pattern, but a small piece of 600 lines per mm diffraction grating is worth less than a dollar. Your mission is to convince the lab people that you are eager physicist material and willing to help clean or repair something if they will just give you a piece of grating so you can do an experiment. You'll make a great contact and really get into physics!