Is the Graph of Lattice Spacing vs Inverse Square Root of Voltage Linear?

[Mathos]

Homework Statement

I'm just making sure I have the correct parameters for a linear graph. The experiment used a diffraction tube to verify deBroglie's hypothesis. The goal is to find the correct lattice spacings in graphite for d(10) and d(11). This might be lacking in pertinent information, but I imagine this experiment is pretty widely done.

Homework Equations

lambda=1.23/sqrtVoltage

sin4(theta)=Diameter/Length to screen

Bragg equation: nlambda=2dsin

The Attempt at a Solution

I think if you plot d vs 1/sqrtV you'll get a linear graph, or at least I thought that. I know this is relatively easy, but I feel like I've just missed something important.

 

[Redbelly98]

Can you post your graph (preferably using a site like photobucket.com or imageshack.com)?

What you expect seems right, but seeing the graph would help.

Another question, what range of voltages are you using? It may be necessary to account for the electrode work function in the value of V.

p.s.
Since "d" refers to the lattice spacing, can we use "D" for the diameter of the diffraction rings?

p.p.s.
For other potential helpers, here is info on electron diffraction tubes:
http://www.telatomic.com/tubes/diffraction_tube.html