Ice in water at 0°C is strained and added to a room temperature, 50% ethanol in water mixture. Stirred with a temperature probe, the iced mixture reaches -2°C.
The stainless steel temperature probe is connected to a Vernier Labquest Mini and LoggerPro software displays a record of the temperature. Two probes can be used, one in the ice water, and one in the room temperature alcohol.
Instead of beakers, thick walled pint glasses are used. A strainer and bowl are needed for straining the ice from the water, showing that the same ice melting in water at 0°C...
It's impossible to magnetically levitate an object with static magnetic fields. However, it's posible to levitate a magnet with another hand-held magnet by taking advantage of eddy currents.
How it works:
A rectangular block of copper (6"×6"×2") is stacked on top of another one (6"×6"×1"). They are separated by 1" plastic spacers. A rectangular bar magnet (2"×2"×½") is placed in the space between them. When a second magnet is lowered from above, the two magnets attact each other. However, rather than "jumping up"...
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...
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.
A rectangular block of copper (measuring 6"×6"×2"), offers VERY little resistance to eddy currents generated by dragging a magnet across its surface. Thus the Lorentz force between the eddy currents and magnetic field is quite strong and you can feel a sizable drag force. Dropping a magnet onto the surface likewise produces a sizable Lorentz force, as evidenced by the damped motion of the magnet's fall. The effects are quite dramatic at liquid nitrogen temperature.