The first right-hand rule establishes the relationship between the direction of the magnetic field and the direction in which the electric current flows through a live wire.
A magnetic field is produced when electrical charges are in motion. In other words, only dynamic electricity can generate a magnetic field; static electricity is unable to do so. In addition, this magnetic field only exists when current is flowing. As soon as the current stops flowing, the magnetic field disappears. Therefore, a link exists between electricity and magnetism, which is called electromagnetism.
In the early 19th century, experiments revealed that a compass needle is deflected when brought close to a current-carrying wire. Thus, it was discovered that a magnetic field is created when electric current flows through a conductor.
The magnetic field around a straight wire always takes the form of concentric circles in a plane perpendicular to the wire. The following image represents the shape of the magnetic field (without orientation) around a straight wire through which electric current flows. Whether the wire is vertical or horizontal, the magnetic field always forms concentric circles around the straight wire.
The shape and direction of the magnetic field lines generated by the current can be determined by using the first right-hand rule; this can be used to determine the direction of the magnetic field around the straight wire. A compass can also help to determine the direction of the magnetic field since it points in the same direction as the field. It will, therefore, be perpendicular to the electric wire.
As the magnetic field rotates on itself, it cannot be said that the magnetic field exits from the north and enters from the south. Therefore, the magnetic field of a straight wire never possesses a North Pole and a South Pole.
To apply the first right-hand rule, the right hand must be wrapped around the straight wire while placing the thumb in the same direction as the electric current (in the conventional direction of the current).
The fingers wrapped around the wire represent the direction of rotation of the magnetic field around the wire (the fingers pointing in the direction of rotation).
There are two ways to increase the strength of the magnetic field around a live wire. However, no matter how strong the magnetic field, it always keeps the same shape.
The greater the intensity of the electric current flowing through the electric wire, the more powerful its magnetic field will be. For example, a live wire with a current five times greater will have a magnetic field about five times stronger.
The use of metals, such as copper, facilitates the flow of electric current and creates a more intense magnetic field.