WAVES
Links checked 24th September 2010
LIGHT
LOWER SCHOOL
This is a nice applet to show the propagation of an electromagnetic wave. And this one shows the emission, transmission, and detection, of the waves very nicely.
This is a very simple one where you can scan through the electromagnetic spectrum, it gives you the wavelength and frequency, the type, and a little image with some information on how it is produced and a typical use.
Move the lamp around, and see how the size of the shadow
changes. (Crocodile clips does this very well)
This is an excellent pinhole camera applet. You can move the object closer or further; you can click on bits of the object to see the light travel through the pinhole; you can increase the size of the pinhole...
This is a brilliant simulation of reflection and refraction of rays and waves from Mr. Fendt. It uses Huygens' construction to show the formation of the wavefronts, in the most simple and elegant way. Fendt for the Nobel prize!
Refraction of light is a nice simple one, with ability to drag the incident ray to a new angle, and to read off the refracted angle for a decent variety of media.
Refraction through a prism, with controllable colour, is well done here. (A Gizmo, which you can only use once...!)
And, by the way, this refraction of light one by someone else is really excellent - it is so simple, but it just shows what matters.
A movable light source at the bottom of a pond shows good internal reflection.
OTHER ELECTROMAGNETIC WAVES
How microwaves heat the water in food in a microwave oven.
An example of the importance of diffraction is resolving two stars which are a very small angle apart (look at end of p.6 and start of p.7 for diagrams).
SOUND
Here is a complete lecture on Sound and Music.
The structure of the Earth
This animation shows recent earthquakes, making clear the boundaries of the plates.
Simple animations of types of Fault, and of types of wave produced
S P waves on surface and in Earth, a good one!
Satellite laser logging of plate movement at NASA
Images of the structure of the Earth, and good information on each layer
UPPER SCHOOL
GENERAL
Polarization by reflection of setting Sun off water (rotate the filter). One, two, and three, polaroids, with source and detector.
Resonance and standing waves by reflection in a box, with explanation. Varying the wavelength is good. I like this simple standing wave on a string, where you can change the driving frequency, and the length of the string, and get resonance. Wave on a string, with an oscillator, beautifully done - as usual - by PhET.
Ruben's demonstration (like Kundt's tube): (also here) a tube with holes, filled with inflammable gas, a loudspeaker at one end, and the escaping gas lit; stunning!
DIFFRACTION
Nice single-slit diffraction display.
INTERFERENCE
Here is two sources of circular waves, interfering. Circular waves from two slits interfering, showing the path difference compared to the wavelength at various points.
Young's slits nicely shown. Here it is with a laser cannon, to indicate the photons. You might prefer this one. Here is another really good, simple, applet for showing the effect of changing slit width and slit separation (and wavelength) on the two source interference pattern. This is excellent for diffraction and interference, from PhET; sound, light, dripping tap, one slit, two slits, ... it is brilliant!
Diffraction grating where you can easily change the number of slits etc. and see what happens. A simple display of the effect of changing the colour.
LENSES
This is a good geometrical optics simulation.
Lens combinations - showing effect of a concave and convex lens in series.
DOPPLER
Simple Doppler effect simulation with the waves spreading out from an ambulance passing a man, who flashes as each wavefront hits him... The Doppler effect is well shown, with circular wavefronts spreading from a source whose speed can be varied. This has a very basic image of a red-shifted star, but it has a link to the sound of a siren passing. This has the spectrum of Hydrogen, and then the spectra from 3 increasingly distant galaxies; you can see the main visible Hydrogen line moving in the red direction.