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# Magnetic Field Pattern due to a Circular Loop (or Circular Wire) Carrying Current

### Magnetic Field Pattern due to a Circular Loop (or Circular Wire) Carrying Current • When current is passed through a straight wire, a magnetic field is produced around it.
• It has been found that the magnetic effect of current increases  when the wire is converted into a circular loop
• The magnetic field lines are circular near the current-carrying loop.
• As we move away, the concentric circles representing magnetic field lines become bigger and bigger.
• At the centre of the circular loop, the magnetic field lines are straight
• By applying right hand thumb rule, it can be seen that each segment of circular loop carrying current produces magnetic field lines in the same direction within the loop.
• At the centre of the circular loop, all the magnetic field lines are in the same direction and add each other, due to which the strength of magnetic field increases.

#### The magnitude of magnetic field produced by a current-carrying circular loop (or circular wire) at its centre is :

• directly proportional to the current passing through the circular loop
• inversely proportional to the radius of circular loop (or circular wire).
• The strength of magnetic field can be increased by taking a circular coil consisting of a number of turns of insulated copper wire closely wound together.
• if there is a circular coil having n turns, the magnetic field produced by this current-carrying circular coil will be n times as large as that produced by a circular loop of a single turn of wire.

According to Clock face rule, look at one face of a circular wire (or coil) through which a current is
passing : (i) if the current around the face of circular wire (or coil) flows in the Clockwise direction, then that face of the circular wire (or coil) will be South pole (S-pole).
(ii) if the current around the face of circular wire (or coil) flows in the Anticlockwise direction, then that face of circular wire (or coil) will be a North pole (N-pole)

if the direction of current in the front face of a circular wire is clockwise, then the direction of current in the back face of this circular wire will be anticlockwise (and vice versa)

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