# Interference pattern, wavelength

1. May 15, 2009

### muffintop

1. The problem statement, all variables and given/known data
Suppose the interference pattern shown in the figure is produced by monochromatic light passing through two slits, with a separation of 127 µm, and onto a screen 1.14 m away. What is the wavelength?

2. Relevant equations
wavelength = (dsin$$\theta$$) / m
y=Ltan$$\theta$$

3. The attempt at a solution
$$\theta$$= arctan (y/L) = arctan (.023 / 1.4) = .941
then plugged it in to get wavelenth. i used m = 2 for 2 slits
wavelenth = 127 x 10^-6m x sin .941 / 2

i think I have m wrong?

2. May 15, 2009

### rl.bhat

i used m = 2 for 2 slits
m is not the number of slits. It is the order of the fringes starting from m=0 for the central bright fringe.