HOME / PRESENTATIONS /

[t]

Jumping Ring

Shoot the ring through the roof after dipping it in liquid N2; Lenz's law induced EMF in metal ring.

What it shows: 

The induced current in a metal ring is dramatically increased by lowering the ring's temperature.

How it works: 

Here is an extension of the ...

Read more about Jumping Ring
Earth's Magnetic Field

OHP representation of lines of force using bar magnet and iron filings.

What it shows:

The magnetic field lines of the Earth can be represented by the field lines of a bar magnet.

How it works:

The Earth's magnetic field is basically a magnetic dipole. It can therefore be represented to first approximation by the field of a bar magnet. The shape of the field lines can be highlighted by the sprinkling of iron filings, or by the use of plotting compasses. The latter method has the advantage of showing the...

Read more about Earth's Magnetic Field
Mixing Air and Water

Three clear containers, about 10% full of water, and three immersion blenders are on the bench. Three students volunteer to mix air into water. To one container is added an egg white, and to another is added xantham gum. The students are met with varying levels of success.

Good containers are 1500 ml beakers. The xanthan gum is best hydrated before the demo, and added as a gel to the water. An equal mix of lecithin and xanthan gum also works.

Pulley Board

Upright board or Blackboard Mechanics with pulley combinations.

pulley board

Orbiter

Ball on string orbits with increasing speed as string is shortened.

What it shows:

An object moving in a circular orbit of radius r has an angular momentum given by:

L = r × mv = mr2ω.

A simple way to show conservation of angular momentum is a ball on a string, whirled around your head. As you change the length of the string, the ball's orbital speed changes to conserve angular momentum.

How it works:

The orbiter consists of a meter length of cord with a wooden ball at one end and a wooden anchor at the other. The cord passes...

Read more about Orbiter
Simple Harmonic Motion Demonstrator

Relation between circular motion and linear displacement on overhead projector.

What It Shows

Uniform circular motion can be shown to be the superposition of simple harmonic motions in two mutually perpendicular directions. This apparatus gives the audience a visual display of how one dimensional simple harmonic motion varies in unison with circular motion.

...

Read more about Simple Harmonic Motion Demonstrator
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.

...
 Read more about Doppler Ball

Pages