Magnetic field is generally interpreted as a region where the force of magnetism acts. This force of magnetism is generally produced as a result of moving charge or some magnetic material. The origins of this interpretation dates back in 19th century. During the early years of 19th century, a scientist named H. C. Oersted discovered that a current carrying conductor produces magnetic effect around it. Although science and technology were not as developed as they are today, based on observations, it was already known that the effect of lightning striking a ship caused the malfunctioning of compass needles, disrupting the navigation system. People back then knew that lightning was a form of electricity and also the fact that the working of a compass is based on the earth’s magnetic field. This suggested a relationship between the two, the moving electric charge (current) and the magnetic field.
Current is generally defined as the rate of flow of charge. We already know that stationary charges produce an electric field which is proportional to the magnitude of the charge. The same principle can be applied here, moving charges produce magnetic fields which are proportional to the current and hence a current carrying conductor produces magnetic effect around it. This magnetic field is generally attributed to the sub-atomic particles in the conductor, for e.g. the moving electrons in the atomic orbitals.
Magnetic field has both magnitude and direction and hence it is a vector quantity and is denoted by B. Magnetic field due to a current carrying conductor depends on the current in the conductor and distance of the point from the conductor. The direction of the magnetic field is perpendicular to the wire. If you wrapped your right hand fingers around the wire with your thumb pointing in the direction of the current, then the direction in which the fingers would curl will give the direction of the magnetic field. This will be clearer with the diagram shown below where the red lines represent the magnetic field lines.
The magnetic field produced due to a current carrying conductor has the following characteristics:
- It encircle the conductors.
- It lies in a plane perpendicular to the conductor.
- Reversal in direction of current flow reverses the direction of the field.
- Strength of the field is directly proportional to the magnitude of current.
- Strength of the field at any point is inversely proportional to the distance of the point from the wire.
Its difficult to comprehend the role of magnetism in our lives as we can’t see them. Take a look around and the realization of its importance will not be as difficult. The motors that are used so extensively around the world whether its a toy car or a bullet train or an aircraft or a spaceship they all use the same magnetic effect. To learn more about magnetic field, quantitative measure of magnetic field produced due to current carrying conductor watch the videos at Byju’s – The Learning App.