Proof magnetic field due to ring …

A solenoid is a long circular coil containing a large number of close turns of insulated copper wire. When a electric current is passed through the solenoid, it produces magnetic field around it as shown in fig. Magnetic field produced by a current carrying solenoid is similar to the magnetic field produced by a bar magnet. As is clear from the figure, the lines enter from the left side and leave out from the right side. If we look from left side, the current appears to be passing in the coil in clockwise direction and hence it acts as a south pole according to clock rule. If the coil is viewed from right side, the current appears to be in anticlockwise direction. Hence, left-hand side face behaves as if this were a north pole. If the coil is left free, it will point South and North.
Since the current in the turns of the solenoid flows in the same direction, the magnetic field produced by each turn of the solenoid adds up, giving a very strong resultant field inside the solenoid. Hence, a solenoid may be used in making electromagnets.