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## Introduction

The flow of charges across a cross-section is known as current, and when current flows through a conductor, it gives rise to a magnetic field. The energy associated with the movement of charges like molecules or ions is known as electric energy. The dynamics of the interaction of two charged particles is governed by Coulomb’s law, which relates the electromagnetic force due to a charged particle on another to their charges and the distance between them.

## What is electricity?

Only materials having free electrons are capable of conducting current, which is defined as the flow of charge across a given cross-section. The flow of charge occurs when some external agent is applied in the form of a potential difference across the ends of the conductor. The energy obtained via the flow of current is used to power various devices in our homes and in industries.

Electric current is of two types, namely, alternating current (AC) and direct current (DC). AC is characterized by the current continuously reversing direction, while DC flows in only one direction.

Current can be generated commercially using the following sources:

1. Burning of fossil fuels can allow us to generate heat energy, which can be converted into electric energy. This is immensely harmful for the environment.

2. Nuclear power is a non-conventional source of energy.

3. Other renewable sources like solar energy, wind energy, and tidal energy can also be used.

## What is electric current?

Current is defined as the flow of charges and in SI units, it is measured in Amperes. Initially, scientists were of the impression that positive charges flow in conductors, giving rise to current. However, it was discovered that it is actually electrons, carrying negative charges, which flow inside conductors. For this reason, the direction of current is now opposite the direction of electron flow.

1 Ampere of current is defined as the flow of 1 Coulomb of charge in 1 second. Mathematically,

In AC current, the direction of the current reverses periodically, while in DC, it remains constant.

## Role of the conductor in electricity

Materials are classified into conductors, insulators, and semiconductors based on their ability to conduct electric current. Conductors can easily and efficiently conduct electricity due to their overlapped valence and conduction bands, which result in more free electrons responsible for current flow. Insulators cannot conduct electricity because the gap between the valence and conduction band is high, making it impossible for electrons to cross. Semiconductors partially conduct electricity due to partially filled valence and conduction bands.

Copper and aluminum are commonly used materials for creating wires in electric circuits, while tungsten is a conductive material with high resistance and low melting point used in incandescent bulbs to produce heat and light energy. Copper windings are also used in motors, generators, and transformers due to their conductive properties. Thus, modern life would be incomplete if we didn’t have conducting materials with us.

## What is magnetism?

Magnetism is a result of the movement of charged particles and is caused by the electromagnetic force, which is one of the four fundamental forces. It is the ability to create an attractive or repulsive force that acts on other magnetic materials. Certain materials become magnetized when exposed to magnetic fields and this phenomenon is known as magnetism.

Magnetic materials are categorized as diamagnetic materials, paramagnetic materials, and ferromagnetic materials. Diamagnetic materials repel magnetic fields and do not get magnetized. Paramagnetic ones can get temporarily and weakly magnetized, whereas ferromagnetic materials like iron retain strong magnetism.

## Magnetic field

The magnetic field is a property that allows magnetic materials to exert magnetic force on other magnetic materials. Magnetic fields are created by all magnets, temporary or permanent, and are diagrammatically represented by field lines. These lines originate at the north pole, end at the south pole, and form closed loops.

A magnetic field is a vector quantity and thus, has both direction and magnitude. A magnetic field is also created when current is flowing through a conductor and the phenomena of magnetism and electricity are closely linked.

Magnetic field

All charged particles experience a magnetic force in a magnetic field given by the following formula:

A quantity that describes the strength of the field is the magnetic field intensity, represented by H, which is related to magnetic flux density and intensity of magnetization as follows:

## Generation of magnetic field

A magnetic field is naturally created around all magnetic fields without external interference. Further, when current flows through a conductor, it gets magnetized and thus, creates a magnetic field of its own. This phenomenon was first discovered in the early 19th century.

The shape of magnetic fields of different magnets can be investigated using a piece of paper and laying out iron fillings on top of it. When a magnet is placed underneath the paper, the fillings align themselves along the magnetic field.

## Difference between electricity and magnetism

 Electricity Magnetism Electricity is related to the phenomenon of current, which is the flow of charges. Magnetism is the phenomenon of certain magnetic materials exerting repulsive/attractive force on other magnetic materials. Static charges can create electric fields. Only moving charges create magnetic fields. A single/electric charge or an electric monopole can exist. Magnetic monopoles can never exist. The two types of charges are positive and negative. The two poles are termed as north and south poles. Used in homes for running devices. Used in fridge doors, induction cooktops, etc.

## Conclusion

This article discussed the concepts of electricity and magnetism. We got to understand how materials are classified into conductors, insulators, and semiconductors. Further, it discussed how electricity and magnetism are linked, as well as what magnetic fields are.

## 1. What is static electricity?

When two charged materials are brought closer, they tend to balance the charge difference that exists between them. This can give rise to sparks and make some materials stick to other materials. This is known as static electricity.

2. Define Coulomb’s law.

Coulomb’s law relates the force experienced by a charged particle due to another charged particle with their charges and the distance separating them as follows:

The constant of proportionality here has a huge value given by

3. What are the properties of electrical conductors?

1. Conductors carry free electrons.

2. They have low resistance. No potential difference or electric field exists inside a conductor.

3. Only free-electrons can conduct electricity.

4. What are the effects of electric current?

Electricity can cause heating, magnetism, and chemical changes in its surroundings.

5. Write some properties of magnetic field lines.

Magnetic fields have the following properties:

1. They never cross each other.

2. They always form closed loops.

3. The density of magnetic field lines represents the strength of the magnetic field.

4. Magnetic field lines go from the south to north pole inside the magnet and from north to south outside.