Driven Damped Oscillator

Single air track glider, with and without variable frequency driver, variable damping, and oscilloscope position vs. time display.

What It Shows

With one end of the car attached via a spring to the end of the track and the other end of the car coupled (via a similar spring) to a driving motor, we can see how the car behaves when it is driven below, at, and above the resonance frequency. Markings on the motor help to show the phase relationships between the driver and car at different frequencies. A storage scope tracks the motion of the car (see Setting It Up...

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Bell Plates

What it shows

Bell plates are polygonal-shaped flat pieces of sheet metal which, when held in the hand and struck with a beater, produce a pleasant, sustained, slightly bell-like tone. Compare this to any arbitrary shaped piece of metal which produces a "clunk" when struck. The sound of the bell plate depends strongly on its shape and even the most modest change in the symmetry (like snipping off a corner) or proportions will make it go clunk when struck.

How it works

Why does a particular shape ring so well,...

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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....

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Black Body Radiation Oven

What it shows:

Black body radiators in thermal equilibrium should emit the same spectrum of radiation, so inside a kiln at high temperature objects should appear the same color whatever their material.

How it works:

Place a piece of brick and an iron ball into a kiln (ours is a Blue M Electric Co. kiln with 25cm × 12cm × 10cm oven) that has a temperature range up to around 1000°C. Close the door and crank up the temperature to maximum. Depending on the type of kiln, it will take around 20 minutes to reach equilibrium (a good...

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The Surface Treatment of Glass

What it shows:

The strength of a material in tension or compression will be affected by discontinuities in its surface structure. This can be demonstrated for glass using microscope slides, and the comparison of failure stress before and after the removal of surface scratches.

How it works:

The slide rests between two custom built test beds (figure 1), the upper bed supporting the load. We use slotted 1kg and 0.5kg masses placed carefully in their holder, and allowing a short time between additions. We find the...

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Reaction of Magnesium and Air

A magnesium ribbon is held with tongs and lit with a match or torch, making a bright flame that consumes the ribbon from the bottom up.

The ribbon should be about 20-30 cm long. Hold the ribbon with the tongs high and at arms length. Let the magnesium ribbon hang at a steep angle but not vertical. Light the bottom of the ribbon by bringing the end of the torch flame up to ribbon.  Magnesium will melt before it lights, so carefully with the torch. The ribbon can also be lit with a wooden match.

Wear safety glasses and don't look directly at the flame.

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