Two slits are 0.158mm apart. A mixture of red light (wavelength = 665nm) and yellow-green light (wavelength = 565nm) fall onto the slits. A screen is located 2.2m away. Find the distance between the third-order red fringe and the third-order yellow-green fringe.
Since they ask for colored fringes, and not dark ones, it must be constructive interference.
x/L = (m*λ/ d)
x = 0.000158m
L = 2.2m
m = 3 (third order fringe)
λ of red = 6.65E-7m
λ of yellow-green = 5.65E-7m
The Attempt at a Solution
I did the equation twice, once for each wavelength.
For red I got x as 2.7E-2m, and for yellow-green i got x as 2.36E-2m.
The difference between these 2 values is 0.0034mm or 3.4mm.
The answer however, is supposed to be 28mm. . .
How was I supposed to do this?