What it shows:

The transmission and detection of radio frequency electromagnetic radiation by use of LC oscillator circuits recreates the discovery by Hertz of a method to generate and detect electromagnetic waves.

How it works:

The core of the apparatus (figure 1) is a series LRC circuit (the R provided by the circuit resistance). The inductor L is a 1m diameter loop made of 1 inch copper tubing which also serves as the radiating antenna. A transformer ¹ supplies 15kV to charge up the capacitor ² until...

What it shows:

A simple qualitative demonstration of total internal reflection using a laser beam.

How it works:

Using a fish tank suitably doped with a scattering agent (see Setting it Up), a ray of light...

What it shows:

In the Heisenberg uncertainty relation, the momentum of a particle cannot be known with any greater accuracy than h/∆x where h is Planck's constant and ∆x is the uncertainty in spatial position. The more you localize its spatial position, the less certain you become about its momentum. An optical illustration for this is the diffraction of light though a slit.

How it works:

For a laser beam, the transverse momentum is pretty well known (i.e. it's zero) but you have no localization of its spatial x coordinate. You...

Laser and plastic lens with curvature to simulate bending of light by massive object.

What it shows:

Gravitational lensing is caused by the bending of light rays by the gravitational field of an intervening object. The effect is seen with the Sun, but is most spectacular when a whole galaxy acts as a lens to a cosmologically distant object, such as a quasar. Depending on the geometry of the alignment and the structure of the lensing galaxy, the image of the quasar is distorted into two or more distinct images, sweeping arcs or a complete ring. Here we model...