Calculating λ in a ripple tank lab

[queenmurr]

Homework Statement

This isn't really an actual homework question but it is regarding a lab so I think it belongs here. In the ripple tank lab I have to trace the nodal lines, plot 3 points in the middle of the 2 lines (one closest to the two sources, one in the middle and one the farthest). From there I use |PnS1-PnS1| = (n-1/2) λ and Xn/L = [(n-1/2) λ]/d to find λ and then compare the values I get with my partner's and explain why some are outliers.

Homework Equations

Why is Xn/L = [(n-1/2) λ]/d not as good as |PnS1-PnS1| = (n-1/2) λ when calculating λ?

The Attempt at a Solution

I think it has something to do with (n-1/2)λ/d not quite equalling 1 but I still don't understand this.

Any and all help would be appreciated!

 

[haruspex]

one closest to the two sources, one in the middle and one the farthest

Do you mean one closest to one source, one closest to the other source, and one in the middle? If not, please explain more.

PnS1-PnS1|

Xn/L

What do all those variables mean?

 

[queenmurr]

Never mind I figured it out, thanks for commenting though! :)