Help with Interference Homework

[CINA]

Homework Statement

I'm doing a lab and it says:

Assume that on the double-slit plate, pattern A has exactly the slit separation printed on the plate. Shine the laser through pattern A onto a screen. Decide whether you will measure positions of maxima, minima, or both. Measure the positions of interference maxima/minima/both. Repeat several times for different maxima/minima and/or different plate-screen distances. Determine the wavelength of the laser by plotting your data and fitting a straight line using d sinθ = mλ and/or (m + ½)λ.

Homework Equations

d sinθ = mλ
L tanθ = y

The Attempt at a Solution

I'm just wondering how exactly one is supposed to plot d sinθ = mλ and fit a straight line through it? We know the d value, the L value, the m value, and the y values. The problem is I don't know what we are supposed to plot so that the slop of a line would be the wavelength. I'm thinking d*y/L = mλ ( using small angnle approximation). Would this work?

 

[Redbelly98]

Looks like there are at least a couple of choices:

You could plot y vs. m, for fixed L.

Or y vs. L, for fixed m.

If both L and m were varied, plotting y/L vs. m should work too.​

In all cases, the slope can be determined from the d*y/L = mλ equation you have.

Hope that helps.

p.s. Yes, normally the sinθ≈θ approximation is valid for the double-slit experiment.