Fraunhofer Diffraction at Multiple Slits

number of slits, cm

15

distance between slits, cm

0.04

width of slit, cm

0.07

distance from center, cm

0.085

wavelength, cm

0.00005

distance of slit to screen, cm

22

plots

combined plot

The intensity in a Fraunhofer diffraction pattern for multiple slits is given by:

I=

2

sin

πbX

λd

2

πbX

λd

×

2

sin

NπaX

λd

2

sin

πaX

λd

,

where

λ

is the wavelength of the light,

d

is the distance of the diffracting slit from the screen,

a

is the distance between slits,

b

is the width of the diffracting slit,

X

is the range of the diffraction pattern on the screen (measured from the center of the space between the edges of the geometrical shadow) and

N

is the number of diffracting slits. The abbreviation a.u. means arbitrary units.