Answer: There is an inverse relationship between the line spacing in diffraction grating and the diffraction angle.
Explanation :
We know that the grating equation is given by :
![d\ sin\ \theta=n\lambda](https://img.qammunity.org/2019/formulas/physics/high-school/qeecol5g3p1z7evb71rp2r18n05ox1jlvq.png)
or
![d=(n\ \lambda)/(sin\ \theta)](https://img.qammunity.org/2019/formulas/physics/high-school/z17zpqaaqqwri2z4wxf1fbfzxv8qfcuen0.png)
where,
d is the distance between two slits or obstacles.
is the diffraction angle.
n is the order
and
is the wavelength of light.
So, the line spacing inversely depends on the diffraction angle.
If the line spacing increases, the diffraction angle decreases because there is an inverse relationship between the line spacing and the diffraction angle.
Diffraction occurs when the light passes through a narrow opening or obstacles.