Magnetism

Introduction 

Since the beginning, magnets have been an integral part of our childhood. It was quite surprising how a magnet bar could grab so many iron nails. In this article, we will be explaining one of the most crucial chapters of physics, which is Magnetism. So, if you want to kickstart your preparation process with us, let’s get started! 

What is Magnetism?

Magnet has the property to repel or attract other substances, which is referred to as Magnetism. When two bar magnets are positioned close to one another, the same poles will repel each other; however, the opposite poles will tend to attract. The primary reason behind this behaviour of the magnet is the imaginary magnetic line that continuously revolves around. Similar to the electrostatic force and the gravitational force, it is also an interaction from a distance. 

What is a Magnetic Field? 

Similar to the gravitational field, the magnetic field cannot be touched or seen. The pull of the earth’s gravitational field can only be felt on the objects around us, and even on ourselves. The existence of magnetic fields can be determined by their effects on different objects such as pieces of metals, copper coil carrying the electric current, and lodestone, a naturally magnetic rock. Let’s understand this via an example- 

Imagine you’ve sprinkled tiny iron pieces or filling on a white paper, along with a magnet bar in between. Every time you tap on the paper, the iron filings will be aligned around the magnet bar. Some properties of the magnetic field lines are- 

• The magnetic field lines do not have an intersection point.
• The magnets’ magnetic field lines build a continuous, closed-loop.  
• The more the magnetic field lines, the stronger the magnitude will be 

Types of Magnets

There are generally three types of magnets- 

• Permanent magnet 
• Electromagnets 
• Temporary magnets  

Let’s understand each one of these in detail- 

Permanent Magnet 

As the name suggests, permanent magnets are those magnets that do not lose their magnetic properties in a lifetime once they are completely magnetised. However, the permanent magnets can be demagnetized if placed at extremely high temperatures or stroking two magnets inappropriately. Generally, there are four major types of permanent magnets. These are- 

• Ferrite or ceramic 
• Samarium Cobalt (SmCo)
• Alnico
• Neodymium Iron Boron (NIB)

Electromagnets

Electromagnets are wire coils that have a ferromagnetic core. In case the electric current passes through the electromagnets, they start to react like bar magnets. Electromagnets do not have permanent magnet pull since these are highly dependent on external factors. 

Temporary Magnet 

The last type of magnet is the temporary magnet. These magnets are magnetised when the magnetic field is present. However, these lose their magnetic property once it’s removed. Some of the examples of temporary magnets are paper clips and iron nails. 

Properties of a Magnet 

The following are the properties of a magnet – 

• Directive property – In the directive property, the magnet is placed in the mid-air using a thread to identify the north pole and south pole of it. 
• Attractive property – according to the attractive property, the magnetic lines of force are the strongest near the south and north poles. 
• Pair property – In case the bar magnets broke, it still has both the south and north pole. No matter how many pieces it splits, it still has both the poles. 
• Law of magnetic poles – When the 2 bar magnets are placed close to one another, the same poles will repel each other; however, the opposite poles will tend to attract.

What is an Electric Field? 

The electric field can be defined as when a single charged particle can excrete force to the extent that other non-charged particles can feel its force. This is often termed the Electric field. The electric field is a vector meaning it consists of both directions and the magnitude. Lines of force are differentiated based on positively or negatively charged particles. If it is positively charged, the force line will be directed outwards; however, it will be directed inwards for a negative charge. 

Magnetic Effect of Electric Current 

The magnetic field force is created by moving electric charges and magnetic dipoles and its ability to excrete force to other magnetic dipoles and moving electric charges. Since it consists of both direction and magnitude, it is termed as a vector quantity. 

Introduction to Gauss Law in Magnetism 

Introduced in the year 1835, Carl Friedrich Gauss stated that Gauss’s Law in Magnetism is related to a net magnetic flux of all closed areas that will be equal to Zero. This law is also known as Gauss’s law theorem. 

Application of Gauss’s Law 

Generally, there are three major applications of Gauss’s Law: firstly, the complex electrostatic problems can be easily tackled through Gauss’s Law. It involves symmetries including spherical, planar, or cylindrical symmetry. Apart from this, there are also instances where the electrical field calculation is complex. Also, Gauss’s Law is used to simplify the process of evaluating the electrical fields. 

Gauss law applications are as follows- 

1. The intensity of the Electric Field because of the prolonged Charged Wire uniformly 
2. The intensity of the Electric Field because of the plane sheet 
3. The intensity of the Electric Field because of the spherical sheet 

Conclusion 

In this article we learned about topics like the magnetic effect of electric current, types of magnet, moving charges and magnetism, etc. It is one of the most crucial chapters of physics. The magnet has the property to repel or attract other substances, which is referred to as Magnetism. When two bar magnets are positioned close to one another, the same poles will repel each other; however, the opposite poles will tend to attract.