Magnetic Field Lines Around A Magnet: 9 Important Facts


Every magnet associated with a magnetic field is responsible for creating magnetic field lines around a magnet to influence the magnetic action on the moving charges or magnetized material.

Generally, the magnetic field is a vector whose direction is specified by the magnetic field lines. Compass is used to know the magnetic field direction, which helps to draw the magnetic field lines around a magnet. In this post, you will learn several facts influencing magnetic field lines around a magnet.

What are magnetic field lines, and what are their properties?

Magnetic field lines are the visual representation of the density of the field around a magnet.

Magnetic field lines are the imaginary line drawn around the magnet to represent the direction of the field traced between one pole to another or between two magnets. Usually, the magnetic field lines emerge from the poles illustrating the casual interaction of the fields.

The magnetic field lines, also called magnetic lines of force, were introduced by famous scientist Michael Faraday. These magnetic field lines are tangential to the magnetic field at any point in space.

magnetic field lines around a magnet
Magnetic field lines around a magnet
Image credits: Wikimedia commons

Properties of magnetic field lines

The properties of the magnetic field lines are listed below.

  • The magnetic field lines are also vector quantities having magnitude and direction.
  • Magnetic field lines can never intersect with one another.
  • All the magnetic field lines possess the same length.
  • Magnetic field lines are continuous and form a closed curvy structure around the magnet.
  • The flow direction of the magnetic field lines depends on the medium.
  • Magnetic field lines always choose the least resistant path between two opposite poles.
  • Magnetic field lines are inversely related to distance. If the distance from the magnet increases, the field line density decreases.
  • The density of the field is higher at the poles.
  • When magnetic field lines are parallel and equidistant from one another, they produce a uniform magnetic field.
  • The magnetic field lines flow from a high to a low permeable region.

What is the magnetic field lines around a magnet?

A qualitative tool for visualizing the magnetic interaction between the two poles of the magnet is the magnetic field lines around a magnet. These lines of force correspond to the region around the magnet where the strength of the field is estimated.

The magnetic field lines around a magnet are the imaginary lines of force that emerge from one pole of the magnet and reach another pole, then travel towards the emerged pole from the interior of the magnet. The magnetic field lines around a magnet also specify the area under the magnetic influence and orientation of the direction of the field.

For example, let us illustrate an experiment using a white sheet of paper, a magnet, and a compass.

  • Place the magnet in the middle of the paper. Take a compass and place it at one pole of the magnet. Now, you can observe that the compass’s needle is pointing toward one particular direction. Mark a dot on the paper using a pencil where the compass points.
  • Now remove the compass from that point and keep it on the dot you have marked before. Now, in the same way, mark a dot on the sheet where the arrow is pointing. This procedure must be repeated until the compass reaches the opposite pole. When the compass reaches another end, join the dots you have marked before. It gives a curved line that represents the magnetic field line.

This process is repeated by placing the compass at different positions near the pole of the magnet, which gives you magnetic field lines around a magnet.

Where is the magnetic field lines of a magnet strongest and why?

The number of field lines around a magnet accounts for the strength of the magnetic field lines.

Near the magnet, the field lines are denser, and at the magnet’s poles, the region where the magnetic field lines emerge out of the magnet. Thus, one can observe the strongest magnetic field lines around the magnet at its pole.

Poles are considered the origin of the field lines from where they emerge. The field lines are more crowded in the region near the magnet; as you go far away from the magnet, the magnetic interaction between the poles decreases, consequently decreasing the field lines’ density.

We all know that moving charges carries a magnetic field, and magnetic field lines can be depicted. If you consider a current-carrying conductor as a magnet, the number of charges available to cause the motion is higher. Thus, emerging magnetic field lines around the conductor are stronger at the poles.

Where is the magnetic field lines of a magnet weakest?

The region where the magnetic field lines are lesser in number is considered the weakest region of the magnetic field lines.

Towards the center of the magnet, the field lines’ density keeps decreasing; thus, magnetic field lines exhibit weak interaction with the material. And also, at the center of the magnet, the magnetic field exhibits little interaction, considered the weakest region.

At the point nearer to the center, the magnetic fields become small, and the contribution of the magnetic dipoles from the field is canceled out partially because of some anti-parallel interaction with the dipole near the center. Because of this reason, the magnetic field lines are weakest at the center and regions nearer to the center.

How does magnetic field lines spread around a magnet?

We know that magnetic field lines form a closed loop structure. This loop can spread out to any extent depending on the size and strength of the field.

The magnetic field lines spread around a magnet in such a way that field lines always tend to point towards the north pole and enter the south pole. The field lines spread out in the region where the magnetic fields exhibit weak interaction and converge at the poles, where the strength of the magnetic field is stronger.

If you consider the earth a giant magnet, the field lines emerge from the earth’s poles and spread out in space in the region nearer to the center of the earth, where the magnetic force of interaction is small. The separation between the lines also increases in the region of the weak field.

Magnetic field lines strength near and far away from the magnet
Image credits: Wikimedia commons

Are magnetic field lines closer near the magnet?

The magnetic field lines are due to the interaction between the opposite poles. Thus, magnetic field lines near the magnet depend on the magnetic field and force.

The magnetic fields are so close to each other near the magnet, and they even converge at the poles because the strength of the field will be maximum in the region close to the magnet.

The magnetic field lines resemble the characteristics of the fluid. As they spread out freely in the space, they diverge more. The separation between each field line emerges from the magnet’s poles, increasing as the points are far away from the magnet. This is due to magnetic field strength and force.

As you move away from the field, the magnetic field lines spread out, and the field interaction becomes weaker. The region nearer to the field indicates the field strength required for magnetic interaction is more so the field lines are close to each other.

Is a bar magnet surrounded by a magnetic field lines?

Every magnet is designated to possess a magnetic field around them. This indeed includes bar magnets as well.

Magnet field lines also surround a bar magnet. These field lines come from one pole and re-enter the bar magnet at another pole. The magnetic field lines surrounding the bar magnet follow a specific pattern that helps to indicate the field’s orientation around the magnet.

A simple experiment can describe the magnetic field lines surrounding the bar magnet using white paper and a bar magnet. First, place the bar magnet at the center of the paper on the table, take some iron filling, and spill it on the paper. Then, tap the table gently so the fillings can spread smoothly around the magnet.

After this procedure, we can observe that the fillings surround the magnet with a specified alignment representing the magnetic field. The direction of these fields can be visualized by drawing the imaginary lines giving magnetic field lines surrounding the bar magnet.

Magnetic field lines surrounding the bar magnet
Image credits: Wikimedia commons

What is the direction of magnetic field lines around a bar magnet?

We already know that magnet field direction is specified by the magnetic field lines around a magnet.

The direction of the magnetic field lines around a bar magnet is pointed from the north to the south pole. They form a close curved pattern around the magnet because it re-enters the magnet at the south pole and again emerges out of the north pole, creating a continuous pattern.

The magnetic field line direction depends on the medium. The direction of the field line from the north pole to the south pole is when the magnet is in a material medium. In the air, magnetic field lines flow from the south to the north pole, creating a closed loop structure.

Earth always resembles a giant bar magnet in the air. The field lines that emerge from the earth’s core are always directed from the south pole to the north pole. This gives evidence that the direction of the field lines is medium dependent.

Conclusion

From this post, we came across many facts about magnetic field lines around a magnet. It shows that magnetic field lines around a magnet visualize the field’s orientation and strength around the magnet. It also gives an account of the field’s medium dependency to demonstrate the flow direction.

Keerthi Murthi

I am Keerthi K Murthy, I have completed post graduation in Physics, with the specialization in the field of solid state physics. I have always consider physics as a fundamental subject which is connected to our daily life. Being a science student I enjoy exploring new things in physics. As a writer my goal is to reach the readers with the simplified manner through my articles. Reach me – keerthikmurthy24@gmail.com

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