This applet shows the simplest case of
diffraction, i.e., single slit diffraction. You can change the color of the light by
draging 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 envolves 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
one considers diffraction through a slit then the properties of the system are wholly
dependant on the ratio / W, where is the wavelength of the light and W is the width of the
slit. If one maps 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. Notice the effect of both
the slit width and wavelength by dragging the slit sides and spectrum selector,
respectively.