Help with Magnetic Fields

Hi I have 2 questions about putting a bar magnet into a coil provided the coil is a completer circuit with an ammeter attached.

1. Does the magnetic field of the bar induce and emf in the coil which in turn induces a current? So does an induced emf cause a current to flow or are they independent?

2. How would the ammeter act when you put the bar in the coil and then came to rest inside the coil? Ammeter would deflect and got back to zero or, it would deflect then all back to a lower reading?

1). The movement of the bar magnet into the coil causes a current to flow, the corresponding emf required to cause this current is called an induced emf.

2). A current is induced only when the magnet is moving in the coil. If you hold the magnet inside the coil and keep it stationary, no current will be induced. Equally, you could move the coil which would cause a change in current.

Thanks. So when you move a magnet into a coil and keep it at rest then the ammeter would deflect and then fall back to zero right?

The reading would return to zero if the magnet was held stationary, yes

I believe Faraday and Joseph Henry carried out this exact experiment in the 1830s. Might be worth having a google if you want to read more about it.

Any other questions and I'd be happy to help.

Just one more question. Say I had a system where there was a constant production of induced currents which in turn produced a magnetic field which in turn produced an induced current and so on. Does the strength of the magnetic field and the magnitude of current decrease as we go further on? What are these effected by if that is the case?

Hmm, I don't really get the question.

Can you give me a physical example of a system where this occurs?

I couldn't give you an example, I made it up. So say I magnet being mechanically pushed into and out of a coil. This coil has an indcued current which would cause it to have a magnetic field itself right? This alternating magnetic field causes another current in another coil. So on and so forth. Will the strength of the field get weaker? This kind of system may not be actually possible btw.

I couldn't give you an example, I made it up. So say I magnet being mechanically pushed into and out of a coil. This coil has an indcued current which would cause it to have a magnetic field itself right? This alternating magnetic field causes another current in another coil. So on and so forth. Will the strength of the field get weaker? This kind of system may not be actually possible btw.