PURPOSE: To demonstrate induction between two coils.

DESCRIPTION: A primary coil is connected to a battery by a key switch, so that closing the switch causes current to flow in the coil and releasing the switch stops the current. Three secondary coils are connected in series with a galvenometer. The primary coil is positioned inside the secondary coil and the current in the primary turned on and off. When the current in the primary coil is turned on, a sharp spike of current appears in the secondary coil. There is no secondary current while the current in the primary remains on at a constant level. When the key is released the current in the primary coil ceases, creating a sharp current spike in the secondary coil of opposite sign to that produced when the primary current is started. The induced current is greater for a secondary coil with more turns. The experiment can be repeated with copper, aluminum, and iron cores.



EQUIPMENT: EME Induction apparatus, primary coil with 7.5 volt battery and key switch, copper, aluminum and iron cores.

SETUP TIME: 5 min.

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