Single-Slit Diffraction
This applet shows the simplest case of diffraction, known as single slit diffraction. You can change the color of the light by dragging or clicking the spectrum selector. You may also change the width of the slit by dragging one of the sides.
Diffraction is a phenomenon which involves the bending of waves around
obstacles. It's generally guided by Huygen's Principle, which states: every point on a
wave front acts as a source of tiny wavelets that move forward with the same speed as the
wave; the wave front at a later instant is the surface that is tangent to the wavelets. If
you consider diffraction through a slit, then the properties of the system are dependent on the ratio 
/ W, is the wavelength of the light and W
is the width of the slit. If you map the intensity pattern along the slit some distance
away, one will find that it consists of bright and dark fringes. In the middle a central
bright fringe can be found, it is the largest bright fringe. The angle at which the dark
fringes occur is given by 
As you see
the intensity pattern is determined only by the ratio / W.
� Copyright 1997, Sergey Kiselev and Tanya Yanovsky-Kiselev
Last modified: June 20, 1997
