## Tuesday, August 30, 2016

### Magnetic Field due to Current Carrying Conductor

In the beginning electricity and magnetism were treated like different subjects. People could not find any relation between them. Electricity is found to be due to the charges and magnetism is thought to be due to the different poles like north and south poles. The force between them and treatment of each subject is done quite separately and they do exist like to separate branches of physics.

In the earlier days of nineteenth century some experiments done by famous scientists found that with the change in the electric field, there is magnetic field also developed around it. This leads to new science called electromagnetism.

The experiments found that the charged particle in the state of rest gives electric field around it. If the charge is moving or if there is a flow of current in any conductor, around it there is not only electric field and there is also a magnetic field.

It can be noticed that the magnetic needle with north and south poles will keep on changing its direction around a electric charge as shown in the diagram.

We can find the direction of the magnetic field using different laws. One of those kinds of rule is Maxwell’s cork screw rule. If there is a nail that rotates using the right hand and if we rotate the screw in such a way that the nail advances in the direction of the current, the direction of the magnetic field is along the direction of the rotation of the head of the nail. It can be understood that the rotation of the head of the nail and the tip of the nail are in the perpendicular plane. Thus electric and magnetic fields are in the perpendicular plane.

We can also use a rule called right hand thumb rule to identify the direction of the magnetic field. It is somehow similar to cork screw rule. If we hold a current carrying conductor with our hand such that the thumb is along the direction of the current, the direction of the magnetic field is along the direction of the curled fingers. It again tells you that the electric field and the magnetic field are in the perpendicular planes.

Around every magnetic pole, there is some space up to where its influence can be experienced. That space is called magnetic field. If we keep any other magnetic pole with in that field, it experiences a force of attraction or repulsion. That force is called magnetic field induction. We can define the magnetic field induction as the force experienced by a unit North Pole placed in the magnetic field.

Around every current carrying conductor, there is a magnetic field and there is a magnetic field induction. To measure that value we have different rules and one among them is Biot-Servert’s law. According to this rule, the magnetic induction at any point directly proportional to the some factors like the  SIN angle it makes with the point, current passing in the conductor, component of the part of the length of the portion of the wire due to which we are measuring the magnetic field and is inversely proportional to the square of the distance of separation.

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