If a sheet containing a single slit is heated (without damaging it) and therefore expands, what happens to the angular location of the first-order diffraction minimum?

Question

Quizplus · Accepted Answer

When the slit expands due to heating, the width of the slit increases. According to the formula for diffraction minima, $d\sin\theta = m\lambda$ (where $d$ is the slit width, $\theta$ is the diffraction angle, $m$ is the order of the minimum, and $\lambda$ is the wavelength of light), an increase in $d$ results in a decrease in $\sin\theta$ for a given order $m$ and wavelength $\lambda$. This means the angle $\theta$ decreases, causing the first-order diffraction minimum to move toward the centerline.

If a Sheet Containing a Single Slit Is Heated (Without