Three long straight parallel wires

The term magnet refers to any material that creates a magnetic field that either attracts or repels other magnetic materials in physics. Whenever a magnet is polarised, it has two poles, which are referred to as the north and south poles. These two poles are always together and cannot be separated; therefore, when we freely suspend a magnet, the magnetic north pole will point to the geographic north pole of the Earth.

In addition to refrigerators, magnets can be found in radios and stereo headphones, as well as audio and videotape players, children’s toys, printer hard drives, and floppies. For the time being, let us review some essential words such as magnetic field, magnetic field lines, and solenoid, before moving on to the magnetic field created by a current-carrying straight conductor.

Magnetic Field

A magnetic field is a force field created by magnetic dipoles and moving electric charges that exerts a force on other moving charges and magnetic dipoles in the vicinity of the magnetic field source.

It is a vector field that exists in the presence of a magnet, an electric current, or a moving electric field in which magnetic forces can be measured, and it is also known as a magnetic field vector field. A magnetic field is created by the movement of electric charges and the inherent magnetic moments of basic particles that are aligned with a fundamental quantum feature known as spin.

Due to the fact that it has both a magnitude and a direction, the magnetic field is considered a vector quantity.

It is represented by the letter B.

Tesla is the SI unit for magnetic field strength (T).

Magnetic Field Lines

Magnetic field lines are imaginary lines drawn around a magnet, and they are continuous closed loops that surround the magnet. The direction of the total magnetic field at any particular point can be determined by looking at the tangent to the field line at that location.

Because the magnet is dipolar, the magnetic lines must have a point of origin as well as a point of termination. This means that the current starts at the north pole and ends at the south pole outside the bar magnet, and it travels back and forth between those two poles while still inside the magnet.

A magnetic field’s relative strength can be determined by observing the closeness of field lines; that is, closer lines indicate a stronger magnetic field and vice — versa. Field lines that are densely packed near the magnet’s poles have more strength.

Magnetic field lines have certain characteristics.

The magnetic field limits are never crossed, and the depth of the field lines indicates the strength of the magnetic field. In many cases, magnetic field lines are closed loops, and magnetic field lines that originate from or begin at the north pole and end at the south pole are frequently found.

What is the best method for determining the direction of the magnetic field produced by the current-carrying conductor?

In the presence of current flowing through a straight current-carrying conductor, a magnetic field is generated around the conductor. Each of the current-carrying conductor’s points has a field line in the shape of a concentric circle, which is represented by the field lines. With the Right-Hand Thumb Rule, which is often referred to as the Maxwell Corkscrew Rule, we can determine how far the magnetic field extends in respect to the direction of electric current flowing through a straight conductor.

Maxwell Corkscrew Rule

If a current-carrying conductor is held by the right hand while maintaining its thumb straight, and if the direction of electric current is in the direction of the thumb, the direction of wrapping of other fingers will reveal the direction of the magnetic field.

How Magnetic Field around a Straight Conductor Carrying Current?

The magnetic field lines that surround a straight conductor carrying current are concentric circles, with the centres of the circles located on the conductor. With the help of a clamp, a piece of smooth cardboard with iron filings dispersed over it is secured in a horizontal position. The magnetic effect of electric current is one of the most important effects of electric current in use, and we would not be able to have motors in the modern world if it were not for its applications. The current flowing through the conductor has an effect on the strength of the magnetic field generated. A straight wire is threaded through a hole in the centre of the cardboard, which has been punched.

A current is passed through the wire by connecting its ends to a battery, which allows it to conduct electricity. When the cardboard is gently tapped, it is discovered that the iron filings are arranged in concentric rings, which is an unexpected result. A current-carrying conductor generates a magnetic field around it, which can be visualised by drawing magnetic lines of force or magnetic field lines through the conductor.

Consider the following scenario: a straight line passes through the plane of the paper and perpendicular to it, allowing us to determine the direction of the magnetic field. Upon placement of a compass needle, the needle comes to rest in such a way that its axis is always tangential to a circular field centred on the conductor’s centre. When the current is flowing inwards, the magnetic field around the conductor appears to be moving in a clockwise direction.

When the direction of the current is reversed, that is, when the current is directed outwards, the direction of the magnetic pole of the compass needle changes as well, indicating that the direction of the magnetic field has been changed. It is now going in the opposite direction as the conductor. Maxwell’s right-hand grasp rule, also known as the right-handed corkscrew rule, is used to determine the direction of magnetic field lines of force around a conducting object. In this way, it can be demonstrated that the direction of the magnetic field is dependent on the current flowing through the conductor.

Conclusion

An observable magnetic field is a vector field that exists in the vicinity of a magnet, an electric current, or a changing electric field, and in which magnetic forces may be detected. Magnetic fields are formed by the movement of electric charges and the intrinsic magnetic moments of basic particles, which are coupled with a fundamental quantum feature known as spin, to produce a magnetic field. In addition to being interconnected, the magnetic field and electric field are both components of the electromagnetic force, which is one of the four fundamental forces of nature.