Interference - Finding distance between slits

[mattbonner]

Homework Statement

A laser is shone through a set of slits and onto a screen.
I have a Δy vs. L graph plotted, where Δy is the spacing between successive nodes, and L is the distance from the slits to the screen. I'm supposed to find the spacing between the center of the slits. The value of λ is given.

Homework Equations

Δy = λL/D
y is the spacing between successive nodes
L is the distance from the slits to the screen
D is the spacing between the center of the slits

The Attempt at a Solution

I have the slope, but I don't know where to go from there...
I'm thinking that the slope will be equal to λ/D? and if I know λ, then I can calculate D. Not sure if this is the right way to go though.

 

[Redbelly98]

I'm thinking that the slope will be equal to λ/D? and if I know λ, then I can calculate D.

Yes, that's right.

 

[nlightner]

It seems like you are on the right track. The slope of your graph should indeed be equal to λ/D. From this, you can rearrange the equation to solve for D, which is the spacing between the center of the slits. Once you have this value, you can use it to determine the spacing between the slits themselves. It is important to note that the value of λ given must match the wavelength of the laser used in the experiment. If it does not, your calculations may not be accurate. Additionally, make sure to double check your units to ensure they are consistent throughout your calculations.