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TEST KEEP CLOSED

THERMAL PROPERTIES OF MATTER

Thermal Expansion

Thermal Conductivity

Jumping Rings

An AC coil with a long iron core produces an alternating magnetic flux, mostly in the region in and near the core. An EMF is induced in a small conducting ring when it is slipped over the core and the power is turned on to the coil. If the ring is solid, a current is also induced. In the case of an aluminum ring, the resulting magnetic force is sufficient to launch the ring several feet into the air. For a copper ring of similar dimensions, the induced current is comparable to that for the aluminum ring, but the mass is substantially greater. The result is an equilibrium position for the copper ring about half way up the core — much less dramatic than the aluminum ring, but still useful to discuss. If a split ring is used, there is an EMF, but no current and therefore no force.

Jumping Rings
Jumping Rings