**Single-slit diffraction**

A single slit, as shown on the right, also causes a diffraction pattern.
This results because the slit is of finite width, and every point in the slit serves as a
source of a wave. Consider a slit of width * a* where we will
consider two points of emission, 1 and 2, one from the upper half of the slit and one from
the lower half. The points will be separated by

For the first **minimum**, * m*
= 1, the formula looks exactly like the expression for the