Answer:
43.16°
Explanation:
λ = Wavelength = 1.4×10⁻¹⁰ m
θ₁ = 20°
n can be any integer
d = distance between the two slits
Since for the first bright fringe, n₁ = 1
n₂ = 2 for second order line
The relation between the distance of the slits and the angle through which it is passed is:
dsinθ=nλ
As d and λ are constant
[tex]\frac{n_1\lambda}{sin \theta_1}=\frac{n_2\lambda}{sin \theta_2}\\\Rightarrow \frac{1}{sin20}=\frac{2}{sin\theta_2}\\\Rightarrow sin\theta_2=\frac{2}{\frac{1}{sin20}}\\\Rightarrow \theta_2=sin^{-1}{\frac{2}{\frac{1}{sin20}}}\\\Rightarrow \theta_2=43.16^{\circ}[/tex]
∴ Angle by which the second order line appear is 43.16°
