Does Magnetic Field Change: 9 Important Facts


The magnetic field relies upon the number of flux lines penetrating through the medium and its permeability of the medium, and the number of free charges in motion.

Several factors are considered for the variation in the magnetic field depending upon the causes for the formation of the field. The direction of the field changes if there is a variation in the strength and the magnitude of the magnetic field.

How does magnetic field change?

The magnetic field decreases with the increasing distance, the same as the electrostatic force, hence the magnetic field changes with distance.

The magnetic field changes with the variable intensity of the magnetic flux penetrating through the material. In the electric circuit, the magnetic field will change if the flow of current through the conductor varies.

The drift of the charges on the conducting surface of an object results in the current flow, and align towards the magnetic flow. This directs the flow of magnetic flux through it, thus strengthening the intensity of the magnetic field. The induced emf is produced due to the fluctuating magnetic field.

When does magnetic field change?

Depending upon the type of the field and the factors responsible for the formation of the magnetic field, the variation in the magnetic field will be governed.

The magnetic field is directly proportional to the magnetic flux, the velocity of the charged particle and its charge, and the angle made by the magnetic flux with the normal of the conductor. The slight variation in these factors will vary the magnetic field.

The magnetic field through the material also depends upon the permeability of the material through which the magnetic flux penetrates. The magnetic flux also increases if the area of a conducting surface is increased; thus, the magnetic field intensity decreases.

Why does magnetic field change?

The magnetic field is constant along the loop. These loops are parallel to each other but meet at the poles, where the intensity of the magnetic field is the maximum.

The magnetic flux lines emerge from one pole and enter through another. Thus the magnetic flux through this area is more in number. The distance between these flux lines increases as the distance between the magnetizing material keeps on rising.

The magnetic field and its strength is optimized by the dipoles comprising in the material. If the temperature of a conductor increases, the magnetic property of the material will vary, thus changing the magnetic field.

The flow of charges and their drift results in the electro-magnetic field. The magnetic field through the coil depends upon the number of turns of a coil, the current flowing through the coil and the area of the conductor. If the current in a coil varies, then the induced emf is set up in the coil, thus changing the magnetic field.

How often does magnetic field change?

The magnetic field through the conducting material changes when there is a variation in the current flowing through the conductor.

The rate of change in the magnetic field is not fixed. Well, it can vary at any time depending upon the factors affecting a magnetic field and the properties of the magnetizing material.

The magnetic field is produced around the charge carrier due to the due electromagnetic force. The induced emf in a conductor equals the change in the magnetic flux flowing through the material.

Does Earth’s magnetic field remain unchanged?

The Earth’s magnetic field is not constant, perhaps it changes at least 10 times in every one million year.

The variation in the magnetic field is due to the weakening of the magnetic strength at the poles. This is associated with the motion of molten lava in the asthenosphere of the Earth.

The Earth’s magnetic field is due to the large content of the ferromagnetic iron accumulated at the centre of the Earth, which is the core of the Earth. The magnetic field lines arise from one pole of the Earth and enter the other pole creating the concentric circles of the magnetic flux lines running parallel to each other.

does magnetic field change
The magnetic field of the Earth is a vector quantity; Image Credit: Pixabay

Due to the magnetic field, the acceleration due to the gravity of the object at the poles is the maximum compared to any other locality on the Earth. Well, the variation in the magnetic field is due to the motion of the matter in the asthenosphere.

Moreover, the moving ions in the molten magma induce the eddy current leading to the formation of the magnetic field around it. This effect comparatively shifts the magnetic poles and is responsible for the weakening of the magnetic strength at the poles, thus shifting the magnetic poles of the Earth.

What happens when magnetic field changes?

As the magnetic field in the conductor changes, the emf and current are induced in the conductor.

With an inevitable change in the magnetic field, the motion of the charges and their drift velocity also differs. Also, the variation in the magnetic field will change the number of magnetic flux through the material, and the direction of the field might also change.

The magnetic flux lines running around the Earth forms the magnetosphere helps to reflect back the radiation incident on the planet’s atmosphere. Suppose the magnetic field strength of the planet weakens, then the planet will be more susceptible to solar radiation, and the rate of the radioactivity of all the elements will increase.

As the magnetic field of the Earth changes, the effect of the magnetic sphere on the planets and the strength of the magnetic field varies for every part of the Earth. With changing magnetic field of the Earth, the speed of the rotation and revolution of the Earth also changes.

With the variable magnetic fields and the continuous change in the magnetic field direction, the magnetic reversal of a planet can also be observed.

Can magnetic field change direction?

The magnetic field is a vector quantity, and its direction varies with time as the magnetic field strength weakens.

The direction of the magnetic field varies if there is a fluctuation in the magnetic dipoles in the material. Thus the direction of flow of current may vary. This results in the variation in the direction of the magnetic field.

The magnetic field is perpendicular to the flow of current and the magnetic force, which is the cross-product of the magnetic field and a current. The direction of the magnetic field is always perpendicular to the displacement of the charges.

The right hand rule is also used to understand the direction of the magnetic field in any scenario. The magnetic will vary with the variation in the current flow in a conductor.

What is the magnitude and direction of the magnetic field at a point situated 5 cm away from the current-carrying wire if the current in the wire is 1.5 A?

Given: The current in the wire is I =1.5 A.

The distance between the current carrying wire and a point is r = 5 cm = 0.05 m.

The formula to calculate the magnetic field due to the current carrying wire is written as,

B=μ0/2πr

Here, B is a magnetic field, μ0 is the permeability of a medium.

Substituting the values in this formula, we get:

Hence, the magnetic field at a point 0.05 cm away from the current carrying wire is 0.60*10-5T and is in the direction perpendicular to the current that is towards the point.

What is the magnetic field in the solenoid of length 15 cm having the 300 number of turns of a coil wound around it and a current flowing through the solenoid is 3 A?

Given: The length of the solenoid is, l=15 cm=0.15 m

The number of turns of a coil around the solenoid is, N=300

The current in a coil is, I=3 A.

The formula to calculate the magnetic field in a solenoid is given as follows,

B=μ0NI/I

Here, μ0 is the permeability of a medium.

Substituting values in this formula, we get:

Hence, the magnetic field in the solenoid is 3.8*10-3.

Conclusion

The magnetic field changes and so does its direction. The direction of the field depends upon the drift velocity and the motion of the charges. The factor responsible for the variation in the magnetic field is generally because of the weakening of the magnetic strength.

AKSHITA MAPARI

Hi, I’m Akshita Mapari. I have done M.Sc. in Physics. I have worked on projects like Numerical modeling of winds and waves during cyclone, Physics of toys and mechanized thrill machines in amusement park based on Classical Mechanics. I have pursued a course on Arduino and have accomplished some mini projects on Arduino UNO. I always like to explore new zones in the field of science. I personally believe that learning is more enthusiastic when learnt with creativity. Apart from this, I like to read, travel, strumming on guitar, identifying rocks and strata, photography and playing chess. Connect me on LinkedIn - linkedin.com/in/akshita-mapari-b38a68122

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