Links checked 20th October 2007
This is a vast
resource, like an alternative text book on every topic. It is at American
university level, so you can understand a lot of it.
Unit 4 (Waves)
I like this model carousel with the balls being swung out as it goes round. You can see the force diagram for each ball, which goes round with it.
SHM with all the graphs for a pendulum, and for a mass on a spring.
A mass on a spring with a x/t graph. You can change m, k, and A, and see what happens. The graphs superimpose. Nice and simple.
Forced Oscillations (Resonance) is very good; you can change the forcing frequency at the top of a spring, and see the effect while the position of the forcing frequency on the resonance curve is indicated.
Resonance and standing waves by reflection in a box, with explanation. Varying the wavelength is good.
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
Propagation of an electromagnetic wave is nicely done here. Transmission and reception of em waves is great here.
This is a very simple one where you can scan through the e.m. 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...
This is a good geometrical optics simulation.
Physics 2000, a useful site for modern Physics. Some good movies and animations (Ian Yems)
The IBM web site has a gallery with a collection of stm images of single atoms etc including the quantum corral, complete with standing electron de Broglie waves. (Rick Marshall)
Build a carbon atom starting from quarks and electrons. I like this one.
This is a beautiful simulation of electrons orbiting a proton/nucleus. You launch your electron at your speed and direction, and it will go into orbit - if you get it right. You can have several running at the same time - and they electrostatically interact with each other.
How about this Photoelectric effect with a quite detailed drawing of the experiment using a variable stopping voltage? You can change the frequency of the incident light, and then adjust the stopping voltage - you see the current fall as the voltage rises. When you get the voltage (only as a stopping voltage, not the other way round!) to be sufficient, a point is plotted on an appropriate graph. This one is helpful, because you can have the voltage both ways round, and you can vary the intensity; it shows I, V, material, intensity, but again no movement - no photon! And here's a third photoelectric effect, very nicely done - the stopping voltage affecting the electrons is beautiful.
What a nice simple idea to have the orbits of the Hydrogen atom with an electron that can be moved from one level to the next, and then changed from a moving particle to a wave! (It gives the energy in J and eV, and the radius)
Bohr atom with energy levels, orbits, and lines produced. You select the orbital, and the transition occurs.
Here is an excellent collection of resources in short videos, including, for example, the move from the plum pudding atom, via Rutherford, to Bohr.
This shows the visible emission and absorption spectra of most elements. This is a clever one: choose a gas, it displays its emission spectrum, and under it a trial spectrum area, and a section where you can put in energy levels, and transitions, which, if they are in the right frequency range, are displayed to compare with those of the actual element. Nice stuff! (This is the same, but just for Hydrogen.) Here is the twin brother, which shows absorption spectra.
Here is a laser explanation showing the atoms becoming excited etc.
Interference of electrons is beautifully shown here; the 2-slit pattern gradually appears. Here is another cartoon version on YouTube.
A home movie of the 1927 Solvay conference, showing all the great physicists involved in the Electron/Photon debate.
{For wave-particle duality, as it applies to electrons in atoms, there is every reason to extend into some of the concepts of Schrodinger's equation. This site seems particularly good.}
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.
Simple orbits - try to get the right starting position and velocity for the satellite to orbit.
And here is you placing an electron somewhere near a proton, without, or with, initial velocity, and seeing its subsequent motion.
This is a good few pages of text, equations, and diagrams, explaining what the Lagrangian Points are. They are important, because - for example - the replacement of the Hubble Telescope will be placed at an Earth-Sun Lagrangian point. {U6 pupils could work out how far out the asteroid needs to be, to orbit with the same period as the Earth and the Moon}
Dull simulation of capacitor charging, but you can change C and R and the charging graph changes immediately, which is helpful. Capacitor charging: This shows the supply voltage, Vc, and Vr, as columns that rise and fall, and shows the electron flow as yellow dots going around. Typically nice work by Professor Hwang in Taiwan.
This shows the resultant electrostatic potential around point charges very effectively; you can change the position and value of the charges
Charges, test charges, forces etc. Very nicely done
This shows the electric field lines around two charges; you can change the charges' positions and values.
Two charges, you click on a point, and it displays the electric field. Also shows the whole field as a collection of little vectors. Nice stuff!
This plots the resultant magnetic fields produced by currents. You can add more wires in.
This shows magnetic deflection of + and - charges in B (very basic). This is a document on magnetic deflection of charged particles, with pictures of the Aurora, equations, and the Hall effect.
The Motor Effect is a very basic one. Look at a setting to the class, and decide which way the wire will move - and then click ' ON' to check.
How about this DC motor? Very nice work, Mr.Fendt! And how about this Generator with the graph of voltage out, ability to pause, and change frequency of rotation. You can remove the field, current, and force, directions to start with.
This is a basic transformer. You can change the number of coils, and it shows them on the core, and the amplitudes of the AC in and out change accordingly.
Unit 6 (Synthesis)
Here's an animated cyclotron. Here's a clear diagram of a linear accelerator. And here's an animated very simple linear accelerator.
The strange world of quantum mechanics by Daniel F Styer is worth a look. (Rick Marshall)
