Electricity & Magnetism Simulation Apps

Fixed Torque Dynamo and Motor:
The Fixed Torque Dynamo and Motor Model solves the coupled differential equations for an electric motor driven by a dynamo (generator). The model can be used as to illustrate elementary instabilities or bifurcations discussed in courses about nonlinear oscillators and dynamical systems.

Servo Motor Position and Velocity Control:
The Servo Motor Position and Velocity Control Model simulates the use of a proportional-integral-derivative (PID) controller to run DC a motor. The motor is modeled as a first order system and the simulation allows the user to control either the position of the motor or its velocity.

RC Circuit Model:
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.

Falling Bar in a B Field Model:
The Falling Bar in a Magnetic Field model displays the non-uniform motion of a conducting bar as it slides along a vertical U shaped wire with resistance R. The apparatus is imbedded in a magnetic field that is B perpendicular to the plane of the bar.

EM Radiation Program:
The EM Radiation program displays the electric field vectors (in the x-y plane) and magnetic field contours (for the field in the z direction) calculated from the Lienard-Wiechert potentials for a charged particle. The default scenario shows the resulting radiation from a charged particle in simple harmonic motion.

Magnetic Field from Loops Model:
The EJSMagnetic Field from Loops model computes the B-field created by an electric current through a straight wire, a closed loop, and a solenoid. Users can adjust the vertical position of the slice through the 3D field.

Magnetic Bar Field Model:
The 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.

Magnetic Multipole Field Model:
The Magnetic Multipole Field Model shows the field of a magnetic dipole or quadrupole with little compasses that indicate direction and relative field strength. A slider changes the angular orientation of the dipole and a movable compass shows the magnetic field direction and magnitude.

Faraday Disk Dynamo Model:
he Faraday Disk Dynamo shows a conducting disk that rotates in a magnetic field. This produces a current (homopolar generator) and for certain configurations, it is a self-exciting dynamo. A self-exciting dynamo is the mechanical analog of a proposed mechanism to produce the earth and sun's magnetic fields .

Electric Generator Model:
The EJS Electric Generator Model shows a simple electric generator made from a conducting loop rotating in a uniform magnetic field and connected to an ammeter. The model shows a plot of the magnetic flux and induced current.

Chaotic Electric Circuit Explorer:
The Chaotic Electric Circuit Explorer Model simulation enables the user to explore the properties and behavior of two electrical circuits with known chaotic behavior. The two circuits are Chua's circuit and an autonomous relaxation oscillator (ARO). The simulation has four modes.

Point Charge Electric Potential Model:
The Point Charge Electric Potential model shows the electric potential produced by N point charges. Charges can be arranged in a ring, a line, or in parallel lines and the charge Q can alternate in sign. Custom configurations can be created by dragging particles.

Point Charge Electric Field Demo Model:
The Point Charge Electric Field Demo model shows the electric field with multiple point charge configurations and vector field visualizations. Users can select these configurations from a drop down menu or can create their own configurations.

Trajectories in Electric and Magnetic Fields:
The Trajectories in Electric and Magnetic Fields model computes a family of trajectories of charges emitted from a point source isotropically and with the same energy. These trajectories create focal points and caustic surfaces meeting the symmetry line in conical cusps.

Point Charge Electric Field & Potential 2D Model:
The Point Charge Electric Field and Potential model explores the concepts of the electric field and the electric potential, in a two-dimensional situation. You can turn on 1 to 5 charged particles.

Electromagnetic Wave Model:
The Electromagnetic Wave model displays the electric field and magnetic field of an electromagnetic wave. The simulation allows an arbitrarily polarized wave to be created. The magnitude of the electric field components and the relative phase between the components of the electric field can all be changed via sliders.

Point Charge Forces in 2D Model:
The Point Charge Forces in Two-Dimensions model investigates the electric force that a charged particle experiences in a two-dimensional situation, because of four other nearby charged particles. The net electric force is shown as an arrow attached to the particle.

Charge Trajectories in 3D Electrostatic Fields Model:
The Charge Trajectories in 3D Electrostatic Fields model investigates a charged particle, and the forces exerted on that charged particle by electric and/or magnetic fields. First, see how the charge behaves when exposed to just an electric field. Then, see how the charge behaves when exposed to just a magnetic field.

Dielectric Breakdown Lightning Model:
The Dielectric Breakdown Lightning Model implements a common method for modeling lightning to simulate the electrical charge buildup during a lightning storm. To simulate the source of the lightning in the cloud, we set the potential to zero and place a small region of negative charge near the top of the grid.

Brewster’s Angle Model:
The Brewster's Angle model displays the electric field of an electromagnetic wave incident on a change of index of refraction. The simulation allows an arbitrarily linearly (in parallel and perpendicular components) polarized wave to encounter the change of index of refraction.

Linear Charge Gauss's Law:
The Linear Charge Gauss's Law model shows a Gaussian surface and allows for the measurement of the charge enclosed and surface area of the surface. Users can change the radius of the linear charge as well as the size of the Gaussian surface.

Model of a Parallel-Plate Capacitor:
A capacitor is a device for storing charge. This simulation, known as a parallel-plate capacitor, consists of two identical metal plates, placed parallel to one another. The capacitor can be charged by connecting one plate to the positive terminal of a battery and the other plate to the negative terminal.

Charge Falling Through a Charged Ring:
This model shows the dynamics of a charged ball as it is released and falls through a ring of charge. The ball and the ring can be charged with a positive blue) or a (red) negative charge in order to change the interaction.

Faraday Disk Dynamo Model:
The Faraday Disk Dynamo shows a conducting disk that rotates in a magnetic field. This produces a current (homopolar generator) and for certain configurations, it is a self-exciting dynamo. A self-exciting dynamo is the mechanical analog of a proposed mechanism to produce the earth and sun's magnetic fields.

Gauss' Law - Point Charge:
This simulation allows the user to investigate the effects of changing the radius of a Gaussian surface and of changing the charge of a point charge on the flux and electric field along the Gaussian surface.

Helmholtz Coils:
ThisModel shows a the magnetic field between two circular coils of wire. The default configuration, known as a Helmholtz coil, sets the separation distance D equal to the coil radius R. These values produce a nearly uniform magnetic field B between the coils

Magnetic Dipole Field 3D Model:
The Magnetic Dipole Field 3D Model displays the field lines and field vectors of a dipole located at the origin and oriented along the z-axis. Users can compute the field line passing through a point by dragging the a marker within the 3D view.

Rail Gun Model:
The EJS Rail Gun Model simulates a rail gun created by running current through long rods generating a magnetic field that accelerates a current-carrying cross-rod. The simulation shows the generated magnetic field.

Charge in Magnetic Field Model:
The Charge In B-Field model simulates moving charged particles in two identical magnetic field regions separated by a zero magnetic field gap.

Faraday Loop in Changing Field:
The Faraday Loop Changing Field Model shows the induced emf in a changing external magnetic field. You can control the frequency, magnitude and type of variation in the external field as you would in the laboratory when using a function generator to produce current in a large coil.

STP Hysteresis Program:
The STP Hysteresis program is a Monte Carlo simulation of a two-dimensional Ising model demonstrating that the magnetization does not immediately change when the external magnetic field is changed.

STP XY Model Program:
The STP XY Model program implements a Monte Carlo simulation of the planar ferromagnet or XY Model of spins on a lattice. The simulation returns the configuration of spins with the option of showing the vortices.

Half Wave Plate Program:
The Half Wave Plate program displays the effect of a half wave plate on an incident electromagnetic wave. The default electromagnetic wave is plane polarized but this polarization can be changed by specifying the components of the wave's Jones vector using the input fields.

Quarter Wave Plate Program:
The Quarter Wave Plate program displays the effect of a quarter wave plate on an incident electromagnetic wave. The default electromagnetic wave is plane polarized but this polarization can be changed by specifying the components of the wave's Jones vector using the input fields.

Jones Program:
The Optics Jones program displays a traveling electromagnetic wave. The default electromagnetic wave is right-circularly polarized but this polarization can be changed by specifying the components of the wave's Jones vector using the input fields.

Blackbody Radiation Spectrum Model:
The Blackbody Radiation Spectrum model shows six fixed-temperature curves between Tmin and Tmax and a red variable-temperature curve that can be adjusted using a slider. The wavelength is measured in nm (nanometer) and the intensity is measured in W.e-5 / (m2.nm).

Charge in Magnetic Field Model:
The Charge In B-Field model simulates moving charged particles in two identical magnetic field regions separated by a zero magnetic field gap.

Magnetic Field from Loops Model:
The Magnetic Field from Loops model computes the B-field created by an electric current through a straight wire, a closed loop, and a solenoid. Users can adjust the vertical position of the slice through the 3D field.

Magnetic Resonance of Spin One-Half Particles:
The Magnetic Resonance of Spin One-Half Particles model simulates the magnetic resonance of a spin ½ particle. Users can vary the frequency of an oscillating magnetic field and see how the quantum spin responds. Users can also vary the magnitude of both the oscillating field and a static field to observe how this affects the resonance.

RLC Circuit with Function Generator Model:
The RLC Circuit with Function Generator model simulates a resistor, capacitor and inductor in series with either a sinusoidal or square wave voltage source and plots the time dependence of the voltage drops across each element. Users can vary the resistance, capacitance, inductance and source frequency.

RC Circuit with Battery Model:
The RC Circuit with Battery model investigates a circuit involving a resistor R, a capacitor C, and a battery. The resistor and capacitor are in series with one another and the battery is switched in series with both components or switched out of the circuit.