Shattering Wineglass

Large speaker with signal generator/amplifier destroys a wineglass; stroboscopic illumination shows vibration mode.

What it shows:

Sound waves of the right frequency are used to excite a wineglass in one or two of its normal modes of vibration. Stroboscopic illumination makes it possible to actually see the vibrations in apparent slow motion. When the intensity of the sound is increased, the large undulations of the glass exceed its elastic limit and cause it to shatter. This can be done in the fundamental or next higher normal mode of vibration ... a beautiful and dramatic...

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Two tuning forks with similar frequencies; one fork is variable in frequency to tune beating.

What it shows:

The interference of waves from two tuning forks of slightly differing frequencies gives rise to beating, that is, a modulated wave of frequency.

νb = (ν1 - ν2)

How it works:

Using two tuning forks of 256Hz, with one of the pair having small clamps (see figure 1) attached to the fork's limbs. These alter the fork's resonant frequency, and adjustment of the clamp...

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Oersted's Experiment

What it shows:

Oersted showed that an electric current produces a magnetic field. His experiment is repeated here on a suitable grand scale.

Oersted's Experiment

How it works:

The current carrying wire in this case is a tubular 22mm diameter copper...

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Hear the Wall Bend

What it shows:  A room-size laser interferometer with audio signal output. A standing wave is produced whenever a wave is reflected back on itself. A resonant cavity requires a second reflection so that the twice reflected wave has the opportunity to be in phase with the original wave. Here, laser light is reflected from a half-silvered mirror (mounted on a wall) so as to return to the laser and be reflected again by the laser. Movement of the wall by half a wavelength is sufficient to change the cavity formed between laser mirror and wall mirror from one resonant...

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Rutherford Scattering

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.


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Adiabatic Heating

Compression of gas within bicycle pump heats gas; alternatively, syringe PV=nRT (w/ Mac TC read-out).

What it shows:

An adiabatic process is one where no heat enters or leaves a system. Here we compress a gas adiabatically inside a bicycle pump. The work done on the gas increases its internal energy, so increasing its temperature in accordance with the first law of thermodynamics.

Increase in internal energy dU = dW the work done on the system

How it works:

Instead of allowing the air out of a bicycle pump we've...

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Greenhouse Bottles

Simulation of the greenhouse effect with silvered and unsilvered glass bottles.

What it shows:

Heat energy readily escapes from a clear glass flask, but is trapped inside a silvered flask which rapidly heats up.

How it works:

Two 2L flat bottom Florence flasks, one clear and one silvered (see reference), have identical 10Ω, 25W resistors placed inside them connected in series to a DC supply 1 These resistors act as good sources of infrared radiation. The clear flask readily transmits the IR, but the silvered...

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Viscous Fluid

What it shows

For a body to reach terminal velocity when falling through a fluid, the drag force (given by Stoke's Law) coupled with the buoyant force (from Archimedes' principle) need to balance the falling object's weight. Leaving derivations to other great texts you end up with


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