This applet plots the slopefield of any linear differential equation, and tries to integrate and plot the solution (given the initial condition).

GeoGebra is not very good at integrating, so it will fail in displaying the exact solution very frequently. The slopefield can always be displayed, even for complicated equations.

## Thursday, May 24, 2012

## Tuesday, May 22, 2012

### Simple molecule

This applet illustrates the simplest model for a ionized hydrogen molecule (two protons + one electron), treated as two hydrogen atoms in the ground state. The user can manipulate the internuclear distance (R).

Questions:

· One of the two states is unable to form stable molecules. Wich one is it?

· What happens to the energy for R >> 0? And for R near to zero?

· Can you estimate the equilibrium distance?

Questions:

· One of the two states is unable to form stable molecules. Wich one is it?

· What happens to the energy for R >> 0? And for R near to zero?

· Can you estimate the equilibrium distance?

## Monday, May 21, 2012

### Semiconductors

This applet shows the simplest model for a semiconductor crystal. It plots the hole and electron densities, letting the user manipulate all the parameters.

Notice that if the Fermi energy raises, the density of electrons in the conduction band and also the density of holes in the valence band raises too. A practical way to raise the Fermi energy is by adding impurities to the crystal.

Notice that if the Fermi energy raises, the density of electrons in the conduction band and also the density of holes in the valence band raises too. A practical way to raise the Fermi energy is by adding impurities to the crystal.

### Fine structure splitting

This applet shows the first energy levels of the hydrogen atom splitted due to the fine structure perturbation. The value of the fine structure constant can be manipulated; using the actual value (1/137) gives an almost imperceptible splitting in the scale of the eV.

## Friday, May 18, 2012

### Parallel reactions

This applet illustrates the kinetics of a simple parallel reaction (also called competing reaction). The applet plots the relative concentration of each compound against time.

### Successive reactions

This applets illustrates the kinetics of a simple two step successive reaction of the form A -> B -> C. The applet plots the relative concentration of each compound against time.

## Thursday, May 17, 2012

### Reversible reaction

This applets illustrates the evolution of a simple reversible chemical reaction of the form A <--> B. It simply plots the relative concentration of each compound against time.

## Wednesday, May 9, 2012

### Number e

This applet demonstrates how the number e can be found by imposing equality between an exponential function and its derivative.

For wich value of a are the two functions identical?

For wich value of a are the two functions identical?

## Thursday, May 3, 2012

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