Analyze ideal gas with the help of this simulation. Ideal Gas with Maxwell's Demon model simulates a two-dimensional ideal gas in a square box, monitored by Maxwell's Demon (which allows only faster than average particles to move from the right side to the left side, while allowing only slower than average particles to move the other way). This simulation can be used as part of the activity described in "The Statistical Interpretation of Entropy: An Activity" by Todd Timberlake, to be published in The Physics Teacher.

This simulation uses Easy Java Simulations (Ejs) to model a two-dimensional ideal gas in a rectangular box, monitored by Maxwell's Demon (which allows only faster than average particles to move from the right side to the left side, while allowing only slower than average particles to move the other way). The particles are initially spread throughout the box with random positions and random velocities (with a Maxwell distribution of speeds). One window shows an animation of the motion of the particles in the box, while another (optional) window plots the temperature of the gas on each side of the box (red=left, blue=right) as a function of time. Note that faster than average molecules are shown as green dots, while slower than average molecules are black dots. Controls:
1. Play/Pause: starts (or stops) the simulation.
2. Step: advances the simulation by one time step.
3. Reset: resets simulations with initial parameter values.
4. Reverse: reverses the velocity of all particles.
5. N: sets the number of molecules in the gas (up to 500).
6. Demon On: checkbox to turn Maxwell's Demon on or off.
7. Temp Plots: checkbox to show a plot of the temperature of the gas on the left (red) and right (blue) sides of the box.
8. Speed (fps): slider to control the speed of the simulation, in terms of the number of frames displayed per second. Higher values make the simulation run faster.

Units are defined so that Boltzmann's constant, the mass of each particle, the length of the box, and the absolute temperature of the whole gas are all equal to one.

You can modify this simulation if you have Ejs installed by right-clicking within the running simulation and selecting Open Ejs Model from the pop-up menu.

In the model, the particles are initially spread throughout the box with random positions and random velocities (with a Maxwell distribution of speeds). One window shows an animation of the motion of the particles in the box, while another window plots the temperature of the gas on each side of the box as a function of time. The user can turn the Demon on/off, or reverse the velocities of all particles. You can modify this simulation if you have EJS installed by right-clicking within the plot and selecting "Open Ejs Model" from the pop-up menu item.

EJS Ideal Gas with Maxwell's Demon model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_entropy_IdealGasMaxwellsDemon.jar file will run the software if Java is installed. EJS is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional EJS models are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or EJS.

Requirements:
* Java

The license of this software is Free, you can free download and free use this graphing software.