Structure of the Earth

Coriolis Effect

As demonstrated by two people throwing a volleyball to each other while sitting on rotating platform.

What it shows: 

The Coriolis force is a pseudo force existing in a frame that rotates with constant angular velocity to a reference frame. It acts on a body moving in the rotating frame to deflect its motion sideways. Here the audience sits in the reference frame, while two volunteers on a rotating platform experience the coriolis force by trying to basket a volleyball.


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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 variation of dip...

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Seismic Wave Refraction

Total internal refraction of laser beam through sugar solution with refractive index gradient; representative of seismic waves through Earth's mantle.

What it shows:

As a simulation of atmospheric refraction, this demonstration shows the gradual and continuous bending of light due to a gradient in the optical density of the medium. In this case the variable refracting medium is a tank of sugar water with a vertical gradient in the concentration of sugar and a HeNe laser provides the light beam. It can be used as a model of mirage formation (except that the...

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Rock Samples

Selection of igneous, sedimentary and metamorphic rocks.

What it shows:

A selection of rocks and minerals available for lecture demonstrations

How it works:

The following samples are available for show-and-tell in lecture. The samples vary in size, and only those marked with a 4 are big enough to be seen.

1. A selection of elements in their natural (unrefined) states:
native copper Cu 4
diamond C iso
gold Au
realgar (silver ore) 4
graphite C hex 4

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Mercator Projection

What It Shows

As shown in the drawing, the Mercator projection is a cylindrical map projection of the spherical globe. The meridians and parallels of latitude on the globe end up appearing as lines crossing at right angles in the projection. Areas on the globe far from the equator appear to be much larger on the projection. It's not trivial to visualize this projection and the intention of this demonstration is to shed some light on it (literally).


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Centrifugal Eggbeater

Spinning frame that demonstrates equatorial bulge (oblateness).

What it shows:

The rotation of a planet about its axis causes its equator to bulge due to the "centrifugal force" acting on its mass. Here a spinning wire frame simulates the effect.

How it works:

Planets are actually oblate spheroids rather than spheres due to their rotation. This device consists of two spring metal rings mounted on a metal axis. The north pole is free to slide so that, as the frame spins, the hoops flatten and the equator bulges. The axis is...

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