KCVS -Modern Physics

Finding new ways to see the world

Modern Physics

Modern physics deals with many concepts that elude simple visualization. The following applets are designed to help address some critical points in a student's understanding. Most are still under development and many have accompanying lesson plans and ancillary files. You can view them from here but will need to go to the downloads page to download these applets.

Motion of Charged Particles in Magnetic and Electric Fields

This is a suite of 4 applets that allow the user to work in either 2D or 3D and to have either magnetic fields alone or both magnetic and electric fields present. Each applet has a measuring tool that enables the user to measure the radius of the trajectory of the particle. User may also select particle type as well as vary the velocity and field strength. Relativistic calculations are sued throughout. Click on the links to run these applets. (Make sure pop-up windows are enabled on your browser.) Teaching lessons are available by clicking on the help menu.

Particle in a Magnetic Field (2D)

Particle in Magnetic and Electric Fields (2D)

Charged Particle in 3D - New Version

This is a new version of the previous applet with a much improved interface. Run Applet

The Cloud Chamber

This applet simulates the operation of a cloud or bubble chamber. The user can select a number of decay modes, adjust magnetic field to match the mode and measure radii or tracks in the chamber. A built in calculator assists the user in measuring particle energy. Run Applet

Compton Scattering

The fundamental particle-aspect of light is illustrated in this applet. A user can select an x-ray photon and observe momentum and energy conserving collisions with an electron. A simple measuring tool enables the user to measure the scattering angle for both photon and electron.
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The Cyclotron

This applet simulates the operation of a cyclotron and helps reinforce the concept of the cyclotron frequency. A variety of particles can be accelerated and the change in energy can be observed graphically. When the cyclotron frequency is not achieved some very interesting trajectories result! Run Applet

Thomson's e/m experiment

The Thomson Experiment applet's schematic drawing. The user can recreate the entire experiment by modifying current and voltage. The user may also choose to view an electron beam, or a moving particle, charge and magnetic pull representations. For comparison and graphing, the data can be collected systematically into a list, to be used in projects, or other programs. Run Applet

The Photoelectric Effect

This applet simulate von Lenard's and Millikan's experiments that provided the experimental understanding of the photoelectric effect and eventual acceptance (albeit reluctant) of Einstein's quantum hypothesis. The applet permits data acquisition for simulated photoelectric effect experiments and contains a library of commonly used metal cathodes.
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If running this applet on a Mac, follow this link.

Particle in a 1-Dimensional Box

This applet helps the user visualize the strange world of the quantum. In this case the classic particle in a 1D box is shown along with the connection between the box, wave functions and energy levels. The user can also relate the 1D-box model to actual molecules that can be described as 1D boxes. Run Applet

Nuclear Stability

This is a beta version of an applet that helps students visualize the conditions for nuclear stability. A graphical comparison is made of the affects of the strong nuclear and electrostatic forces as well as the effect of asymmetry in nuclei. The applet can also be used to estimate nuclear binding energies. Run Applet

Radioactive Decay

In this applet radioactive decay is illustrated via a simulated Geiger counter. A database of radioactive elements (sorted as alpha, beta or gamma emitters) provides ample data . Students can plot the decay and fit a decay curve to the data and from this determine the half-life of the element. Run Applet

Nuclear Potential - Strong Interactions

This is a beta version of an applet that helps to illustrate the forces involved in the binding of nucleons. In the current case a pair of protons are brought together. The resulting potential energy for the configuration is displayed. Run Applet

Millikan-Like Experiment

This is a beta version of the classic Millikan experiment. It is not, however, as complex as the actual experiment. The user sees one drop at a time and the assumption is that it falls in a vacuum. By adjusting the voltage between the plates the student attempts to have the drop reach terminal velocity. From this the charge on the drop can be deduced.

Follow this link to a complete suite on Millikan which includes a demonstration of air resistance effects and a link to a much more realistic JAVA applet simulating the Millikan experiment.
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If running this applet on a Mac, follow this link.

The Rutherford Experiment

This applet allows users to visualize what Rutherford believed would happen when he conducted his famous gold-foil experiment by interacting with a "raisin-bun" model of the atom. Run Applet
This applet presents a historical recreation of the Geiger-Marsden experiment in which the existence of the nucleus was first established. The applet can be used to generate data for student analysis. Run Applet
After performing the Geiger-Marsden experiment, Rutherford theorized a new, nuclear model of the atom. By interacting with his model, users can test his model and compare it to the Thomson model. Run Applet
In this applet the user can investigate the behaviour of alpha particles as they interact with various nuclei. Data can be represented graphically or in tabular form for further analysis. Run Applet
Scattering from various shapes and force laws can be illustrated with this applet. The applet can be used to help illustrate how scattering experiments can be used to elicit information about underlying structure. Run Applet
A link to a complete suite of digital learning objects as well as a brief introduction to the Rutherford experiment and links to literature about the experiment. Run Applet