Magnetic Field And Magnetic Field Lines

Similar to how an electric field surrounds a charge, we can consider a magnetic field surround a magnet. We know that a magnet attracts small pieces of iron even when they are a certain distance away from it. Thus, the magnetic force, like electric force and gravitational force, acts at a distance. The idea of force acting at a distance can be easily understood by introducing the concept of field. We imagine a magnet as giving rise to a magnetic field, which exists, in the whole space surrounding it.

What is a Magnetic Field?

Generally, magnetic field is defined in the form of a picture (example below) which describes how a magnetic force is distributed in the space around and within something magnetic.

Magnetic Field Lines

Well, most of us know something about magnetic objects. Rather we might have experienced that there are some force acting between them. Basically, the phenomenon of magnetism is mediated by “magnetic field” – i.e., an electric current or magnetic dipole creates a magnetic field, and that field, in turn, imparts magnetic forces on other particles that are in the fields. All materials are influenced by this force to a greater or lesser degree.

The force that one magnet exerts on another can be described as the interaction between one magnet and the magnetic field of the other. A convenient method to describe magnetic field around a magnet is to draw field lines around it.

How does magnetic field occur?

If you are wondering how Magnetic fields occur. Well, it occurs whenever a charge is in motion. That being said if you apple more charge in the motion the strength of a magnetic field usually increases. Besides, Magnetism and magnetic fields are part of the electromagnetic force which is indeed one of the four prime forces of nature.

How is magnetic field illustrated?

Typically, a magnetic field can be illustrated in two different ways.

Mathematically, it can be described as a vector field. The vector field can be marked directly as a set of many vectors which can be drawn on a grid. In this case, the vector points that are pointing in the direction of the compass has length dependent on the strength of the magnetic force. All in all, it simply means magnetic field is a vector quantity that has both direction and magnitude.

Magnetic Field And Magnetic Field Lines

There are two different vectors that are usually used to represent magnetic field. The first one is the magnetic induction or magnetic flux density which is symbolized by B and the other one is called the magnetic field intensity or magnetic field strength. It is symbolized by letter H.

Apart from vectors, it can be represented with the use of field lines. Magnetic field lines are nothing but imaginary lines. Here, the density of the lines indicates the magnitude of the field. Taking an instance, the magnetic field is stronger and crowded near to the poles of a magnet. As we move away from the poles it will be weak and we can see by the lines, they becoming less dense.

Magnetic Field And Magnetic Field Lines

The are some of the basic concepts about magnetic field but it is enough to make you understand about the concept. Learn more about magnetic fields and their behavior with our expert faculty here at BYJU’s.


Practise This Question

State true or false.
If a conducting wire is placed along the x-axis and a current flow through it in the positive direction, it creates a magnetic field around it. The direction of the magnetic field at a point (0,-2) is negative z-axis i.e. inside the plane.