Question

When the flat open side of a charged coil was brought near the flat open side of the coil connected to a galvanometer (both coils parallel to each other), the galvanometer deflects very little. How do you know they need to be parallel and why is this the case? Where is north and south if the coil is acting like a bar magnet?

Answer 1

Explanation:

According to Faraday's laws, say coil 1 has current flowing in it and coil 2 is just connected to the galvanometer, when two coils are brought to parallelly each other, the magnetic field lines of coil 1 is dense near its conducting wire and they are circular to the wire so that coil 2 can be in maximum contact of the changing magnetic field produced by coil 1 and that's how induced current and emf are produced in the coil 2, and this induced current is the reason behind the deflection of galvanometer.  

When charged flat coil are brought parallelly near to the coil which is only connected to galvanometer, the galvanometer deflects very little because:

Coils store energy in the form of magnetism which is known as inductance of the coil so when this charged coil is brought to the second coil the changing magnetic field is produced until the magnetic energy in the charged coil is consumed to produce the induced current in the second coil. So, for this reason deflection in galvanometer is very little i.e. induced current passes through the galvanometer until the magnetic energy of the charged coil is completely consumed. According to Faraday’s laws of electromagnetism, when both coils are parallel, second coil can be in maximum contact of electromagnetic field of charged coil because magnetic field lines are circular and dense near the conducting wire.

According to Lenz's laws if the induced current is produced counter-clockwise direction in the second coil then coil will act as a north pole of magnetism whereas if the induced current is produced clockwise direction in the second coil then coil will act as a south pole of magnetism.