Homework SourseI cant get this problem figured out the seventh dark fringe
I can\'t get this problem figured out. the seventh dark fringe is located .029 m to the side of the central bright firing on a flat screen which is 1.1m away from the slits. separation is 1.5E-4.meters what is the wavelenght of light.
Solution
given
slits are seperated by d = 1.5*10-4m
distance from the slits to screen L = 1.1m
the seventh dark fringe is located y =0.029 m to theside of the central bright firing on a flat screen
we have the condition for destructive interference as
dsin =(m+1/2)*
or sin = (m+1/2)*/d
here m= 7
we also have the linear distance from the central brightfringe to the seventh dark fringe as
y =Ltan
or tan = y/L
as is small tan˜sin
so
(m+1/2)* /d= y/L
or = yd /(m+1/2)*L
= 0.029 m*1.5*10-4m / 7.5*1.1m
= 527*10-9m
= 527nm
