Program Editor Java

The Ejs Wave Packet model displays the motion of an approximate wave packet. The simulation allows an arbitrarily wave packet to be created. The default dispersion relation, with the frequency equal to the wavenumber, results in a wavepacket that does not spread. The amplitude, maximum and...

The QM Probability program displays the time evolution of the position-space wave function and the associated probability density. The default wave function is the n = 5 state in a ramped infinite square well. Additional states and other potential energy functions can be specified using the...

The EJS Magnetic Bar Field Model shows the field of a bar magnet and has a movable compass that reports the magnetic field values. The bar magnet model is built by placing a group of magnetic dipoles along the bar magnet. You can modify this simulation if you have Ejs installed by right-clicking...


Platforms: Mac

The QM Measurement program displays the time evolution of the position-space wave function and can be used to simulate the quantum-mechanical measurements of energy, position, and/or momentum. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the qm_measurement.jar file...


Platforms: Mac

The STP TemperatureMeasurementLJ program simulates the exchange energy between a demon and a system of particles interacting via the Lennard-Jones potential. The program shows the kinetic temperature of the system as a function of time, and the energy distribution of the demon. The purpose of...


Platforms: Mac

RC Circuit models the dynamical behavior of a voltage source attached in series to a resistor and capacitor. The source voltage can be chosen to be either a 10 volt sinusoidal or square wave with an adjustable frequency. Users can examine and change the model if they have Ejs installed. The RC...


Platforms: Mac

The Ejs Normal Modes on a Loaded String model displays the motion of a light string under tension between two fixed points. The string is also loaded with N masses located at regular intervals. The number of masses on the string can be changed via textboxes. You can modify this simulation if you...


Platforms: Mac

The Ejs Action for the Harmonic Oscillator model displays the trajectory of a simple harmonic oscillator by minimizing the classical action. The simulation displays the endpoints of the motion (t,x) which can be changed by using the textboxes or dragging, and displays the new trajectory as well...


Platforms: Mac

The Ejs Duffing Chaos model computes the solutions to the non-linear Duffing equation, which reads, x'' + 2?zN*x' - x (1 - x2) = f cos(?Ya* t), where each prime denotes a time derivative. The simulation displays two solutions with different initial positions and a plot of phase. The evolution...


Platforms: Mac

The Ejs Anisotropic Oscillator model displays the dynamics of a mass connected to two opposing springs. The simulation displays the motion of the mass as well as the trajectory plot. The initial position of the mass can be changed by dragging. The unstretched lengths of the springs can changed as...


Platforms: Mac

The Levenberg-Marquardt Fitting of Nuclear Decay Model demonstrates how EJS can be used to fit experimental data. In this simulation, nuclear decay data are used to provide a simple example, but this same process can be applied to any type of data. The sum of squared deviations is minimized but...


Platforms: Mac

The 3-D Hydrogen Atom Probability Densitites model simulates the probability density of the first few (n = 1, 2, and 3, and associated l and m values) energy eigenstates for the Hydrogen atom (the Coulomb potential). The main window shows the energy level diagram for the solutions to the Coulomb...


Platforms: Mac

The Ejs Orbiting Mass on a Table 3D model displays the frictionless dynamics of two masses that are attached via a string through a hole in a horizontal table. Mass m moves on the table in two dimensions while mass M hangs vertically and just moves up and down. The simulation allows displaying...


Platforms: Mac

The Heating and Cooling a Cylinder model computes the radial temperature distribution within a long cylinder as it is heated and cooled by a surrounding fluid. The cylinder is broken into shells and the temperature of each shell is computed using a finite difference approximation to the radial...


Platforms: Mac

The Two Dimensional Schrodinger Equation model simulates the time evolution of a two-dimensional wave packet as it moves towards a slit with an obstacle in it, both with variable widths. By changing three parameters via sliders provided, slit width, obstacle width, and initial position of the...


Platforms: Mac

The EJS Electric Multipole Model of a point charge (monopole), a dipole, or a quadrupole can show either field vectors or the scalar potential (voltage). A slider changes the charge and a movable detector shows the electric field direction and magnitude or measures the potential. Detector values...


Platforms: Mac

The Ejs Duffing Poincare model computes the solutions to the non-linear Duffing equation, which reads, x'' + 2?zN*x' - x (1 - x2) = f cos(?Ya* t), where each prime denotes a time derivative. The simulation displays the solution Poincare plot. The evolution parameters can be changed via textboxes....


Platforms: Mac

The STP EinsteinSolidHeatBath program simulates the exchange of energy between an Einstein solid and a heat bath. The purpose of this simulation is to determine the properties of a Einstein solid at different temperature T and to compare our results with analytical calculations of the...


Platforms: Mac

The STP IsingMeanFieldSolution program uses Newton's method to calculate solutions to the mean-field approximation to the equation of state of the Ising model. The program also displays the free energy as a function of the magnetization m for given values of T and the magnetic field H. The...


Platforms: Mac

The Circular Well Superposition simulation displays the time evolution of the position-space wave function in an deep 2D circular well. The default configuration shows the first excited state with zero angular momentum. Additional eigenstates can be added using a button in the eigenstate...


Platforms: Mac