This applet illustrates the change in amplitude, wavelength and phase of electromagnetic
waves as they cross a boundary between two different optical media. The modelled wave interacts
with the boundary at normal incidence. This applet allows you to vary the optical parameters of
the wave, specifically the amplitude, wavelength and speed of the wave, and also allows you to alter
the refractive index of the two materials. There are also options to change the type of wave,
from a simple Gaussian ‘bump’, to a sinusoidal wave, to a ‘photon-like’ representation, a
combination of a Gaussian bump and sinusoidal wave. The applet also allows you to view either
all parts of the wave or simply the continuous components, as well as allowing the user to look
at either the electric or magnetic field
This applet has been built with Processing and makes use of the
G4P (GUI for Processing) library.
The sliders can be used to change several parameters of the interferometer:
Length of second arm – This controls the position of the second mirror
Reflectivity: beam-splitter – This controls the power reflectivity of the beam-splitter
Reflectivity: first mirror – This controls the power reflectivity of the first mirror
Reflectivity: second mirror – This controls thepower reflectivity of the second
When the electromagnetic wave hits the boundary at normal incidence, part of the wave is reflected
backwards, in the opposite direction to the incoming wave. The reflected and incoming waves interfere
with each other, adding together to give a resultant wave on one side of the boundary, in the first material.
When the wave hits the boundary part of the wave is transmitted through the second material.
The transmitted wave and the wave resulting from the interference of the reflected and incoming waves must
have the same value at the boundary, due to boundary conditions derived from Maxwell’s equations. These
boundary conditions state that, for materials with no free current or charge density, the components of the
D- and B-fields normal to the boundary
must be continuous and the components of the E- and H-fields parallel to the boundary must be continuous.
