Answer: 6.64 × 10^ -6 m
Explanation:
for a constructive interference;
ρ= 2πm
remember that we are looking for the seventh bright side fringe.
so, m=7
ρ=14π
We now have to find the phase different
ρ`=2πx/ρ - 2πx/ρ
p` is the wavelenght in the mica. x= width of the mica wavelength in the mica.
ρ= ρ/n.
n= refractive index.
The phase will now be
ρ`= 2πx/ρ - 2πx = 2πx(n-1)/ρ.
ρ= ρ`
14π = 2πx (n-1)/ ρ
we now solve for x; x = 7ρ/n-1
x = 7(550× 20^ 9)/ 1.58 - 1
= 6.64 × 10^-6
