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Sodium Absorption

What it shows:

Sodium 'D' line absorption showing up as a black line in the yellow of a continuous spectrum. Good as a simulation of the sodium portion of the Fraunhoffer absorption spectrum caused by atoms in the solar atmosphere; it does not however, resolve the 5890/5896Å doublet.

How it works:

As in the Sun, which is a black body source surrounded by an atmosphere of cooler gas containing many heavy atoms including sodium, we can set up a black body spectrum using a slide projector, and provide a hot sodium 'atmosphere' using...

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Bernoulli Wind Tunnel

What it shows

Bernoulli's Principle states that the pressure exerted by a fluid is velocity dependent; the faster the velocity the lower the pressure. This can be demonstrated by a form of Venturi tube, a pipe with a narrow constriction which forces an increase in fluid velocity.

How it works

The varying cross-section of the wind tunnel forces air to travel its length at different velocities, with the highest velocity being at its most constricted part. From equipartition of energy, the increased energy in one degree of freedom (the kinetic energy of the flow)...

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Shoot the Monkey

Monkey released from platform is shot by simultaneously fired cannon.

What it shows:

This is a demonstration of the independence of the horizontal and vertical components of velocity of a projectile. Often referred to as "the monkey and hunter," the problem is the following. A hunter (at ground level) aims a gun at a monkey hanging from a branch high in a tree. The monkey, being very intelligent, does not want to be shot. It knows that light travels faster than bullets and reasons that, if it lets go of the branch the instant it sees the flash of the gun,...

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Barton's Pendulum

Ten coupled pendulums of different lengths; shows resonance and phase.

What it shows:

All objects have a natural frequency of vibration or resonant frequency. If you force a system—in this case a set of pendulums—to oscillate, you get a maximum transfer of energy, i.e. maximum amplitude imparted, when the driving frequency equals the resonant frequency of the driven system. The phase relationship between the driver and driven oscillator is also related by their relative frequencies of oscillation.

How it works:

Barton's Pendulum...

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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...

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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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Brewster's Angle

What it shows:

When unpolarized light is reflected from a non-metallic surface, the reflected ray is plane polarized parallel to the reflecting surface if

θi + θr = 90°

or

tanθi = n

where θi = incident ray (Brewster's angle), θr = refracted ray, n = refractive index

How it works:

We use a black vinyl sheet 1m×4m as the reflecting surface, which has a Brewster angle of 57°. A theatrical spot lamp 1 is used to give a 50cm circle...

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Stonehenge

Static model of site; can be used with light source to simulate a mid-summer's morning.

What it shows:

1:50 scale model of the Stonehenge site with the positions of Sun and Moon on important dates marked. It can be used with a light show to reproduce Sunrise on Midsummer's morning, June 21.

How it works:

The Stonehenge site consists of the sarsen circle of 30 megaliths capped with 30 lintels. Within this circle is a horseshoe pattern of five trilithons. 80m north-east of the circle's center is the Heel Stone; it is the...

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