Does The Magnitude Of Magnetic Field Change: 7 Crucial Facts


In this article we shall answer the question- Does the magnitude of magnetic field change? Before that we shall know what factors influence the value of magnetic field.

Magnetic field is the measure of magnetic influence on electric charges, electric currents and materials that show magnetism. These particles experience a force that is perpendicular to their motion. The value of magnetic field flux depends on the strength of the individual poles.

What is magnetic field?

It is a vector field which is used to describe the magnetic influence on electrical charges and materials that follow magnetism.

We cannot see magnetic field but we can visualize it. We can represent magnetic field using magnetic field lines. These lines tell us about the intensity of the magnetic field. The places where the field intensity is more the field lines will get dense and vice versa.

How does magnetic field arise in a coil?

An alternating current produces magnetic field when it is passed through a coil. A coil comprises of a iron rod wounded with a current carrying coil.

When the alternating current passes through the coil, a magnetic field is generated between the electric poles and these poles start acting as magnetic poles. Vice versa happens when a varying magnetic field is passed through the coil an EMF is generated.

when does the magnitude of magnetic force change?

The magnetic force depends on the intensity of the magnetic field, particle velocity, charge of moving velocity and angle between the velocity and magnetic field.

If any one of the above factors is changed then the magnitude of magnetic force will also change. Magnetic force can be given by the formula discussed in the section below-

F=qvBsintheta

magnitude of magnetic field depends on what

Magnetic field is affected by many factors. The factors include amount of current passing, number of turns in the coil and radius of circular loop. These factors are discussed in detail in the section given below-

  1. Amount of current passing – The amount of current passing through a coil directly affects the magnitude of magnetic field. The magnitude of magnetic field is directly proportional to the amount of current passing through the coil. More the current flowing more will be the intensity of the magnetic field.
  2. Number of turns in the coil – Number of turns is a very important factor that affects the magnitude of magnetic field. The magnitude of magnetic field will increase as the number of turns in the coil increase.
  3. Radius of circular loop – A lot has been discussed about how magnetic field is affected by the radius of circular loop. As we increase the radius of the coil, the magnitude of magnetic field keeps reducing. It follows an inverse relationship with the radius of the coil.

What changes magnitude of magnetic field

In above section we discussed about the factors that affect magnetic field. If value of any one of the factor changes then the magnitude of magnetic field will also change.

The factors affecting the value of magnetic field include the amount of current passing through the coil, number of turns in the coil and radius of coil. The magnetic field is directly proportional to number of turns of the wire in loop and the current flowing in the coil. The magnitude of magnetic field follows an inverse relationship with the cube of distance.

How does the magnitude of magnetic force change?

The factors that affect the magnitude of magnetic force are discussed in the above section. When any of these properties change, the value of magnetic force also changes. The strength of magnetic field has a lot of influence on the magnetic force.

If we change the strength of the poles then the magnitude of magnetic field will change, this will result in changing the magnitude of magnetic force as well. Similarly if we change the angle of the coil, or velocity of the particle we will see that the magnitude of magnetic force has also changed.

Where does the magnitude of magnetic force change?

The magnetic force will change where the magnetic field’s magnitude is changing. We can observe that the magnetic field has highest intensity where the lines are most dense because the field lines will converge at the poles and diverge as we move away from it.

The magnetic lines get crowded near the poles. The magnetic field hence is greatest at the poles. So we can say that the magnetic force is least in the mid way of the magnet and keeps on increasing at the poles. Near the poles we will experience the highest magnitude of magnetic force.

Does magnetic field decrease with distance?

The magnetic field will reduce as we keep going farther from the wire. This is certainly because the field lines will keep getting scarce and less dense away from the poles. This is because the fact that the field lines converge at poles and diverge as we go away from the poles.

The magnitude of magnetic field follows an inverse relationship with the cube of distance. That means the magnetic field strength is affected severely as the distance increases. It keeps on decreasing drastically as we keep moving away from the wire. The density of the field lines also decrease.

Does the magnitude of magnetic field change
Image: Magnetic field lines of a horse shoe magnet

Image credits: Wikipedia

Why does magnetic field reduce with distance?

The magnetic field will have highest intensity at places where the field lines are most dense. This happens near the area closest to wires and poles. As we go away from the poles the number of field lines per unit area starts reducing hence the magnitude of magnetic field.

The field lines start from poles and end at poles. The field lines make a loop by coming out from one pole and going back to another. So the lines get accumulated near the poles/wires and get less dense when the distance increases. So the magnitude of magnetic field also gets lesser and lesser as the distance increases. Mathematically we can say that magnetic field is inversely proportional to third power of the distance from the wire.

Conclusion

We saw that the magnitude of magnetic field weakens out as we go away from the wire. It can be visualized by drawing field lines converging near the poles and diverging when it they go away from the poles.

Abhishek

I, Abhishek Khambhata, have pursued Btech in Mechanical Engineering. Throughout four years of my engineering, I have designed and flown unmanned aerial vehicles. My forte is fluid mechanics and thermal engineering. My fourth year project was based on performance enhancement of unmanned aerial vehicles using solar technology. I would like to connect with like minded people.

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