[★★★]

Elastic and Inelastic Collision Model

What it shows:

Two cars have the same mass and same spring bumper. When given a push and allowed to collide with a wall, one car bounces off with only a small reduction in speed ("elastic" collison) whereas the other car comes nearly to a complere stop ("inelastic" collision).

How it works:

There are two impulse cars made of identical materials and have the same mass. The car that models an elastic collision has all its lead sinkers securely attached to the frame so that they can't move. In contrast, the car that models an inelastic collision has the lead sinkers...

Read more about Elastic and Inelastic Collision Model
55 Gallon Drum

What it Shows

With an air pressure of 105 Nm-2 at sea level, even a heavy duty oil drum will be crushed if it has nothing inside to balance the pressure.

How it Works

The screw cap on the drum is fitted with a vacuum pump connector. Simply turn on the Varian SD-200 pump and wait—it usually takes a few minutes to pump down, so you can carry on with what you were doing interrupted by various creaks and bangs as the drum's side walls begin to give. Because drums of this size are ribbed for strength, they can hold up under the strain, but when it...

Read more about 55 Gallon Drum
Doppler Ball

Plastic Wiffle Ball with built-in shriek to throw past (or at) your audience.

What it shows:

Waves emitted from a moving source are Doppler shifted to higher frequencies when moving toward the observer, and shifted to lower frequencies when moving away. This audio demonstration is also a useful analog to the optical red shift and blue shift exhibited by astronomical sources moving relative to the Earth.

How it works:

A plastic Wiffle-Ball™ is filled with foam padding to protect an enclosed mini-speaker 1 and its...

Read more about Doppler Ball
Jumping Wire

What it shows:

A current carrying wire in a magnetic field experiences a force at right angles to both the field and current directions. The wire will jump up or down, depending upon the current direction.

How it works:

On a microscopic scale, the electrons in the wire experience a Lorentz force due to the magnetic field,



the force perpendicular to both field and velocity vector. On the...

Read more about Jumping Wire
Spectrum Piano

The visible part of the electromagnetic spectrum is represented by less than an octave of the keys; UV, IR, and microwaves are also indicated.

What it shows:

The keys of a piano are used to represent the electromagnetic spectrum, illustrating the narrow range of frequencies that constitute the portion visible to human sight.

How it works:

An old piano 1 with its center octave of keys (C4=261.6Hz to C5=523.3Hz) colored for the visible spectrum (the seven colors spread to...

Read more about Spectrum Piano
Malus' Law

What it shows:

Polaroid filters absorb one component of polarization while transmitting the perpendicular components. The intensity of transmitted light depends on the relative orientation between the polarization direction of the incoming light and the polarization axis of the filter and is described quantitatively by Malus' cos2θ intensity law.

...

Read more about Malus' Law
γ Ray Inverse Square Law

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...

Read more about γ Ray Inverse Square Law
Meissner Effect

What it shows:

A superconducting material in the presence of an external magnetic field excludes that field from its interior. This is shown by levitating a magnet above a high-temperature superconductor.

...

Read more about Meissner Effect
Precipitation of Lead Iodide

Potassium iodide solution is added to lead nitrate solution, and bright yellow lead iodide precipitates.

Potassium iodide solution is 0.1 M and lead nitrate solution is 0.01M.

The lead nitrate solution is about 350 ml in a 600ml beaker, and the KI sol'n is 200 ml in a 400ml beaker. Pour the potassium iodide sol'n into the lead nitrate.

Glasses and gloves. The finished demonstration is stirred and the precipitate and solution goes in the hazardous waste bucket.

Archimedes' Principle

What it shows

Archimedes' principle states that the buoyant force or upthrust is equal to the weight of fluid displaced. An object with equal mass but a lower density occupies more volume so displaces more water; it therefore experiences a greater upthrust.

How it works

This demo compares the buoyant force acting on two 1kg masses, one of aluminum and one of brass. Each in turn is lowered into a beaker of water using a spring balance (figure 1). The aluminum, having the lower density, experiences the greater upthrust and a reduction in weight from 10N to about...

Read more about Archimedes' Principle

Pages