Young's Double Slit Experiment w/ White Light & Water

[songoku]

Homework Statement

1. What will happen if we use white light as the source of young's double slit experiment?
2. If the experiment is done in water, what will the effect to the y_n? y_n is the distance of n^th fringe from center fringe.

Homework Equations

d sin θ = nλ
d y/D = nλ

The Attempt at a Solution

1.
I'm not really sure. Will we get some colors of light on the screen like dispersion by prism? If yes, why? Is it because white light consists of several color so each of the color will make different interference pattern because of the difference of wavelength?

2.
The value of y_n will decrease because the wavelength will decrease. Am I right?

Thanks

NB : Is there a term for y_n? We call the separation of adjacent fringes is fringe separation, so what is the term for the distance of n^th fringe from center bright?

 

[Dadface]

Your answer to number one is correct,each wavelength will produce its own pattern and all the patterns will overlap.
Your answer to number two is correct.
If you know the equation for fringe separation you can easily answer the question you set in your footnote.

 

[songoku]

Hi Dadface

Equation for fringe separation :

w = λD/d, but what is the relation to the term of y_n?

Thanks

 

[Dadface]

Hello songoku, distance from centre of the first order fringes =1*w,distance from centre of second order fringes=2*w and so on.For the nth order fringes distance =nw.

 

[songoku]

Hi Dadface

hm...maybe I don't state the question clearly because of my poor English. I'm not looking for the formula, but I want to know what the "name" for y_n is. Like what I wrote before :
the separation of adjacent fringes = fringe separation

y_n = distance from center bright to n^th fringe = ...? maybe it is called n^th fringe?

Thanks

 

[rl.bhat]

The formula for yn is given by
yn = n*d*lamda/D, where d is the slit width and D is the distance between slit and the screen.
Now what happens to the wavelength when the light travels from air to water?

 

[Dadface]

Hi Dadface

hm...maybe I don't state the question clearly because of my poor English. I'm not looking for the formula, but I want to know what the "name" for y_n is. Like what I wrote before :
the separation of adjacent fringes = fringe separation

y_n = distance from center bright to n^th fringe = ...? maybe it is called n^th fringe?

Thanks

You can call it the nth bright fringe.To be more precise the central fringe is called the "zero order fringe".The two bright fringes either side of that are called the "first order bright fringes"and so on.Your question was referring to one of the "nth order bright fringes"

 

[songoku]

Hi rl.bhat and Dadface

Thanks a lot !