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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...

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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.

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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...

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DC Circuit Puzzlers to Ponder

The circuits are built into large wood boards that mount easily onto an easel. The boards are labeled using conventional symbolism. Bulbs and batteries are easily removable--just be careful not to burn your fingers on the hot bulbs!

Parallel vs Series Circuit

Which bulb will be brightest in each circuit?

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Blackboard Optics

What it shows:

With an assortment of plane and curved mirrors, convex and concave lenses, parallel-sided block and prisms, the Klinger 1 Blackboard Optics Kit© allows one to demonstrate all the classic examples in geometric optics by actual ray tracing in two dimensions.

How it works:

All components in the kit are magnetically attached to the blackboard. The light source produces a grazing pencil of light on the surface of the board which may be refracted through, or reflected from, the various optical components. Single...

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Copper and Bulb

Copper has positive temperature coefficient; light bulb gets brighter when copper leads are dipped in liquid N2.

What it shows: 

Copper has a positive temperature coefficient (≈ 3.9×10-3 per ˚C), which means that its resistance drops with temperature. Here copper wire is immersed in liquid nitrogen (77˚K = -196˚C), decreasing its resistance (from room temperature) by almost a factor of 2, thus increasing the current flow though a circuit.

How it works: 

We have a coil of 30AWG copper wire...

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