Electricity and magnetism are closely related. A magnetic effect is created when an electric current travels through copper wire. Hans Christian Oersted was the first to detect the magnetic effects of electric current. The magnetic field is a field created by magnetic dipoles and from moving electric charges, and due to the magnetic field, it exerts the forces in the nearby moving charges. The magnetic field has both direction and magnitude, and hence it is a vector quantity. The magnetic field shows the strength of a magnet and the direction of the magnet’s force. The magnet’s strength is represented by magnetic field lines from north to south and south to north inside and outside the magnet.

What is magnetism?

A magnet has the property to repel or attract some other substances, 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 attract. The primary reason behind this behaviour of the magnet is the imaginary magnetic line that continuously revolves around it. Similar to the electrostatic force and the gravitational force, magnetism is also an interaction from a distance. 

Compass needle

A compass needle is a small magnet. A north pole is the end of the compass that points north, while a south pole is an end that means south. Magnets with like poles repel one another, while magnets with opposite poles attract each other. The compass needle is a small instrument that helps find the magnetic field’s right direction. The needle consists of a small metal needle, and it directs in a different direction due to the magnetised needle. The needle aligns with the magnetic field of the Earth and points in the direction.

Magnetic field and field lines

The magnetic field can be defined as a measure of the magnetic force that can be observed by interacting particles in a certain space. The magnetic field can arrange the magnetic objects in the direction of the field. For example, Earth’s magnetic field makes a magnetic needle compass and other magnetic objects line up in the direction of the field.

• Magnetic force lines always originate from the magnet’s north pole, making a curve and entering the south pole. They pass through the magnet’s south pole and again come back to the north pole, forming a circle around the magnet.
• Two magnetic lines of force can never intersect because that would mean there are two directions, which is not possible.
• Where the magnetic field is strong, the lines of the curve are close. When it is weak, the lines of the curve are further apart.
• The lines of force of a uniform magnetic field are parallel and at equal distances.
• Lines of force in a magnetic field are imaginary lines that show the surface direction of the magnetic field in that place.
• A tangent drawn at any point on the magnetic force lines shows the magnetic field’s direction at that point.

Magnetic field due to a current-carrying conductor

The conductor’s form determines the magnetic field pattern created by an electric current passing through a conductor. The magnetic field produced by a current flowing through a straight conductor (wire) is proportional to its distance. The field lines around the wire are concentric circles, with the right-hand rule determining their orientation. 

Fleming’s left-hand rule

According to Fleming’s left-hand rule, stretch the thumb, forefinger, and middle finger of the left hand in a mutually perpendicular direction. If the forefinger points in the magnetic field direction and the middle finger in the current direction, then the thumb gives the direction of force. 

Magnetic field due to a current through a circular loop

The concentric rings depicting the magnetic field surrounding a current-carrying circular loop would get larger and larger as the distance from the wire increased. When the arcs of these large circles approach the circular loop’s centre, they look like straight lines.

Magnetic field due to a current in a solenoid

A solenoid is a coil made up of numerous circular turns of insulated copper wire tightly wound into a cylinder form. The magnetic field of a current-carrying solenoid is comparable to that of a bar magnet. When magnetic material is placed within the coil, a strong magnetic field created inside the solenoid may be utilised to magnetise it. An electromagnet is a magnet that has been produced in this way.

Conclusion

Magnetic effects of electric current help understand the force created by magnetic dipoles during the flow of electric charges. Magnetic fields are essential for understanding many aspects of life on Earth, including the navigation of ships and the movement of climate systems across the Earth’s surface. Magnetic field lines offer a useful visualisation method that allows scientists to determine the effects of the Earth’s magnetic field on day-to-day human life and natural phenomena on the planet.