Question

Regarding double slit diffraction. Using the formula y/L=mλ/d I have to find d. I therefore rearranged the formula to get d=mλ/(y/L).
λ=6.65x10^-5cm
y=0.17446512cm
L=39cm
What value do I use for m?

Answer 1

it must be given in the question

Answer 2

It's not given in the question.
The question is to determine the value of d by varying the distance of L and measuring the centre of the diffraction pattern and the mth bright spot. it's a lab prac.

Answer 3

if it helps here's the graph I made http://desmond.imageshack.us/Himg832/scaled.php?server=832&filename=graphv.jpg&res=landing and I measured from -0.00009740607239 to 0.001647245121 to get the y value then converted that to cm. I just don't understand how I'm meant to get m.

Answer 4

Is m the amount number of the brightspot away from the centre brightspot?
in otherwords if I measured from the top of the centre bright spot to the top of the one next to it to get y would it just be 1?