In what two ways can you increase the strength of an electromagnet

In this post, we’ll study some methods and facts about how to increase the strength of an electromagnet.

Electromagnets; consist of two words electro+magnet, which simply means that it is a temporary magnet that creates a magnetic field around it when the current (movement of electric charges) passes through it. It’s a device that is made up of conducting wire (usually copper) wrapped around some magnetic material, i.e. soft iron.

How to determine the strength of an electromagnet

As we know, Magnetic field is produced around a current-carrying conductor or wire. To determine the direction of the magnetic field produced by the conductor, hold the conductor in right palm, such that your thumb is pointing in the direction of current then the curled fingers will show the direction of magnetic field.

We can increase the intensity of the magnetic field by winding the wire in a helix structure over a ferromagnetic material. Atoms of iron are randomly oriented in the absence of an external magnetic field in such a way that the individual magnetic field cancels out. Under the influence of current, the atoms are forced to reorient in a particular direction which generates an intense magnetic field.

The magnetic field strength of an electromagnet is given by,                                                                      

B= kμ0 nI

The relationship between k and μ is given by,

μ= k μ0

Here,   k is relative magnetic permeability,

            n is the number of turns per unit length,

            I is the current flowing through it,

μ0 is the permeability of free space,

μ is the permeability of material.

Relative permeability

The magnetic permeability of most of the materials is very close to the magnetic permeability of air, while the magnetic permeability of the iron or ferromagnetic materials are very high. The term which compares the ability of the material to become magnetized to the air’s magnetic permeability is known as relative permeability. If the value of it is more than one, then it shows that the material is more magnetic than the air.

How to increase the strength of an electromagnet

Do we know how we can make a stronger and even stronger electromagnet?

Let’s see,

The magnetic field intensity of an electromagnet can be increased in three ways; 

By increasing the current

As soon as we increase the amount of current in an electromagnet, the atoms start to align in the same direction creating an exhaustive magnetic field. The more atoms reorient themselves in the same direction; the more will be the magnetic field.

There comes the saturation point when all the particles have reoriented themselves perfectly in the same direction, beyond this point, no matter how much current you will increase, it won’t strengthen the magnetic field further.

By Increasing the number of turns

A number of turns are associated with individual magnetic fields generated by it. Each and every turn acts as the individual source of the magnetic field.

As we know, the strength of the magnetic field generated by a wire decreases as the distance increases from it. In order to get a strong magnetic field, the number of turns should be more, and the windings must be close to each other.

Using a magnetic material as a core

The copper wires are wrapped on the magnetic material; why not on wood?

Suppose we use the wood and wrap the copper wires on it. We see that the magnetic field is not as strong as it used to be, when we have used soft iron material as a core. In Spite of having the same dimensions as the iron had, the magnetic field strength is not the same.

What’s the reason?

The physical quantity, magnetic permeability which is inherent property of material. It shows how much the material is attracted by the magnetic field. Roughly, we can say that the more the material is conductive, the more its magnetic permeability.

The ferromagnetic material allows the passage of magnetic flux through it, while materials like wood which is non-conductive, do not allow passage of it. Hence, when we use the soft iron core, it gets magnetized as it allows the magnetic field and becomes a temporary magnet until the current is passed through the coil.

Problem 1

An electromagnet has a core of material of magnetic permeability 6.3 *10-3  H/m. The number of turns is 1000 per meter. A current of 2A flows through the solenoid. Find magnetic field intensity in core.

Solution:-

Given,

μ= 6.3*10-3 H/m

n = 1000 turns per metre

I = 2 A

B=kμ0nI

As we know, μ= k μ0, Hence

B= 6.3*10-3*1000*2

B= 12.6 N/A m

Problem 2

An electromagnet has a core of relative magnetic permeability 4000 and the number of turns is 500 per meter. Calculate the magnetic field intensity when current of 10A flows through it.

Solution:-

Given,

k= 4000

n = 500 turns per meter

I = 2 A

B=?

As we know, the magnetic field intensity is given by

B=kμ0nI

B= 4000*4π*10-7*500*10

B= 251.2 N/Am

Frequently asked questions: FAQs

On which principle does an electromagnet work?

It works on the principle of electromagnetisms, which tells us that a closed magnetic field is produced around a straight wire which carries current.

What are the advantages of electromagnet?

The main advantage of the electromagnet is,

we can change its polarity (north or South Pole) by swapping the poles of battery (reversing the current),unlike permanent magnets. The magnetic field can be increased or decreased as per our convenience. The magnetic field’s effect can be removed by stopping the flow of current through the coil or by switching off the battery.

What are the disadvantages of using an electromagnet?

The main disadvantage of an electromagnet is that it heats up quickly. It requires larger space and the magnetic field is not constant as it is not a permanent magnet.

Does the thickness of wire affect the magnetic field intensity of an electromagnet?

As we know that the resistance of the material depends upon its dimension.

R=  ρL/A.

Where, L is the length, A is the area and ρ is the resistivity of the material. Hence, the thicker wire, the less will be resistance which allows more current to flow through it results in a stronger magnetic field.

What are the applications of an electromagnet?

There are many applications of electromagnet

How is the magnetic field produced?

Magnetic field is produced by 1) magnet 2) by current carrying coil 3) by changing electric field 4) by a moving charge.

Is there any magnetic field due to thermal motion of electrons?

No, because the average velocity of electrons due to thermal motion is zero and hence the magnetic field is zero.