When you move a magnet into a coil of wire, the changing magnetic field induces an electric current in the coil due to electromagnetic induction. This phenomenon is described by Faraday's law of electromagnetic induction.
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Moving the Magnet Into the Coil: As you push the magnet into the coil, the magnetic field within the coil changes, which induces a current. The ammeter will show a reading, indicating a flow of current. The direction of the current depends on the orientation of the magnet and follows Lenz's law, which states that the induced current will flow in a direction that opposes the change in magnetic flux.
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Stopping the Magnet: Once you stop moving the magnet (keeping it stationary inside the coil), the magnetic field through the coil becomes constant, and the induced current drops to zero. Consequently, the ammeter reading will return to zero.
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Pulling the Magnet Out: When you pull the magnet out of the coil, the magnetic field again changes, but this time it is decreasing as the magnet is moving away. This change in magnetic flux also induces a current in the opposite direction (again based on Lenz's law). The ammeter will show a reading reflecting this current flow, which will again depend on how quickly you are pulling the magnet out; a faster pull will induce a stronger current.
In summary, moving the magnet into the coil generates a current in one direction, stopping results in no current, and pulling the magnet out generates a current in the opposite direction.
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