Question

In order to create a double slit diffraction pattern, 600 mm light is shone onto a narrow slits 1 um apart. There is a wall 10 m behind the slit.

A) Where on the wall in relation to the point directly behind the slit are the three brightest bands?

B) How wide is each band?

C) Rank the three bands in order of brightness

Answer 1

for double slit diffraction, the bright fring appears at m*wavelength*screen distance/slit width

where m=order of the bright fringe

so putting the given values,we get for m=1,2 and 3, the distances are 6m, 12 m and 18 m

B)width of the band=wavelength*distance of screen/slit width=6 m

C) as intensity decrease with distance, the band at 6 m is brightest and band at 18 m is least bright.