Principle 8.11.1. Single-Slit Diffraction.
The location of dark spots due to light shining through a single slit on a distant screen can be determined by \(a \sin\theta = p \lambda\) for \(p = 1, 2, 3, ...\text{.}\)
Section 8.11 Single-Slit Diffraction
Single-slit diffraction is an interesting case where we still see this interference of light, even when there is only one single slit.
By using Huygen’s Principle (Principle 8.7.1), we can effectively look at how two different waves, travelling within the single slit, might interfere with one another. We can find where the dark spots are located by using a similar method as we used for two-slit intereference.
Exercises Single-Slit Diffraction Activities
1.
What differences do you notice between the single-slit diffraction pattern on the screen and the double-slit interference patterns you have seen previously?
2. Single-Slit Diffraction Simulation.
Play with the
light interference simulation for a few minutes. Click on the "Diffraction" tab.Write down some observations. Play with different opening shapes. For the square shape, what happens when you change the width? What happens to the image as you change the frequency of the light?
3. Width of a Diffraction Pattern.
The width of the central bright maxima in a single-slit diffraction pattern can be measured by looking at the distance to the first dark spot. What happens to the width as the distance between the slit and the screen increases? What happens to the width as the wavelength decreases? What happens as the slit size decreases?
