Observe the decay of airborne radionuclides with a Geiger counter and computer. (OK, it's not new since we've been doing the experiment for 20 years...we just neglected adding it to our list.)

... Read more about Radon's Progeny Decay

What it shows:

β-rays emanating from a radioactive isotope are deflected from their straight line paths by a magnetic field.

How it works:

⁹⁰Sr/⁹⁰Y, a "pure" beta-...

What it shows:

Gamma rays are electromagnetic radiations which we detect as quanta of energy or photons. When the radioactive source is confined so that it acts as a point source, the diminution in the number of photons incident on a given area is such that the intensity is inversely proportional to the square of its distance from the source.

How it works:

A Co-60 source (1.173 and 1.332 MeV gammas) radiates isotropically. A Geiger-Müller counter is used to detect the radiation intensity at distances of 2, 3, and 4 meters. The...

What it Shows

The interactions of the various radiations with matter are unique and determine their penetrability through matter and, consequently, the type and amount of shielding needed for radiation protection. Being electrically neutral, the interaction of gamma rays with matter is a statistical process and depends on the nature of the absorber as well as the energy of the gamma. There is always a finite probability for a gamma to penetrate a given thickness of absorbing material and so, unlike the charged particulate radiations which have a maximum range in the absorber...

What it shows:

Radiations originating from atomic and nuclear processes are classified into four types:

charged particulate radiation consisting of
1. heavy charged particles (α)
2. fast electrons (β)
uncharged radiation consisting of
3. electromagnetic radiation (γ, x-ray)
4. neutrons (n)

The interaction processes of each type of radiation explain their penetrability through matter, their difficulty or ease of detection, and their danger to biological organisms. The interactions of these radiations with matter are unique and the...

What it shows

How could the fluorescence of the glass in a Crooke's tube generate x-rays? This was the question Henri Becquerel addressed in 1896. His experiments with fluorescence in uranium salts and subsequent discovery of radioactivity are recreated in this demonstration.

How it works

Instead of uranium salts, we use a green glass candy dish—the green glass being uranium glass, a popular consumer item in the 1950's! The green glass fluoresces brilliantly when illuminated by UV (a "black light") and, although not particularly "hot," a Geiger-Mueller counter held...

When the electrons in a cathode ray tube collide with the glass, they decelerate rapidly. The radiation emitted by the electrons is called Bremsstrahlung or braking radiation.

What it shows

In 1895, Wilhelm Röntgen...

A beam of cathode rays (electrons) impinging on a paddle wheel cause it to spin and travel down the vacuum tube.

What it Shows

A paddle wheel is suspended by its axle inside a Crookes tube so that when the paddle vanes spin the entire...

What it shows:

Potential energy curve with potential barrier illustrates electron-atom, atom-atom or ion-ion interactions.

How it works:

This is a one dimensional potential well model with a potential hill that can be used to represent several scenarios. The wooden model is made of a sandwich of three strips of plywood (1/4"-1/2"-1/4") forming the cross section as shown in figure 1. A 1" ball bearing fits snugly enough into the groove that it won't fly out when it hits the barrier.

figure 1. The roller...

Orbital motion simulated by ball rolling on wooden potential well.

What it shows:

Motion in a central potential is demonstrated by a ball rolling on a circular 1/r curved surface.

How it works:

The 1/r potential well simulates the gravitational potential surrounding a point mass; a ball bearing moving in this potential follows a parabolic or elliptical orbit depending upon its initial trajectory and velocity. As it loses energy due to friction, the orbit decays and the ball spirals towards the centre of the well. You could...

What it shows:

A qualitative demonstration of Rutherford's α-particle scattering experiment using magnetic pucks on an air table.

How it works:

In its simplest form, we use an Ealing air table, ¹ 1m square, with a fixed magnetic puck at the center. A second puck with the same polarity is repelled and scattered by the first; the scattering angle being dependant upon the impact parameter b (see figure 1). A more complex setup is described in the Comments.

...

What it shows:

Ball bearings simulate atoms in a lattice sitting at local potential minimums. Giving them energy excites the atoms and they oscillate about their equilibrium positions in these wells; only with large amounts of energy can they be truly dislocated.

How it works:

A piece of wood 100 × 25 × 2cm acts as the ‘potential’ structure of the lattice. The atoms, 3cm diameter ball bearings sit at the bottom of a cosine varying potential cut to about 10cm depth in the wood by a jig saw.The balls are held in the 2-dimensional...

...

What it shows:

Perturbation by colliding atoms in a high pressure gas result in the broadening of emission and absorption lines. This is clearly seen in the sodium D (589nm and 589.6nm) lines of a high pressure sodium lamp.

The broadening in frequency width is dependent upon the separation of the perturbing particles (Novotny 1973) by

∆ν ∝ r^-n

With n=2 the broadening is due to the coulomb field of an ionized atom or electron; this is the linear Stark effect. With n=3 the interaction is between neutral atoms of the same type; this...

What it shows:

Unlike the continuous spectrum emitted by blackbody radiators, the light given off by atoms in a gaseous discharge is characterized by its discreet nature. Using street lamps for the light sources, bright atomic spectra of mercury or sodium are projected onto a screen.

...