Diffraction

Diffraction


 * Diffraction**- the process in which light or other wave is spread out due to passing through a aperture or across and edge.

This is the single slit diffraction equation where θ = the angle between normal line and light ray, m = the order number (1,2,3,..), a = the slit width, and λ = the wavelength of the light.
 * Single Slit Diffraction Equation:**

**Single Slit Diffraction Applet**


 * Changing Wavelength**: As a result from these three pictures we learn that when the wavelength of the light is changed the amount interference bands change and the color change. As you can see at the lower wavelength we can see 9 purple bands. This continues to change as the middle shows 7 green bands. And finally at the biggest wavelength we see 5 red bands. In conclusion from this as the wavelength increases the amount of bands decrease.


 * Changing Slit Width:** As we see by the pictures below, the only thing affected by the change in slit width is the number of interference bands. In the pictures we see that the smallest slit width (picture 1 below) leads to the least amount of interference bands and the larger slit width (picture 3 below) has more bands.




 * Changing the slit to screen distance:** What we learn from this is basically that when the distance from the slit to the screen is increased, the less amount of interference bands we can see on the screen.



Sometimes light can pass through a circular shape instead of a rectangular slit. Some real life examples of this would be a telescope lens or the pupil of the human eye. The image doesn't have a distinct point in this situation, it consists of a circular bright region in the center and alternating dark and light rings around it.
 * Diffraction by Circular Aperture:**


 * Equation:**

This is the Diffraction by Circular Aperture equation where θ = the angle to the first minimum, d = diameter of the aperture, and λ = the wavelength of the light.

Sources: single slit applet- http://www.surendranath.org/Applets/Optics/Slits/SingleSlit/SnglSltApplet.html