The working principle of electromagnets relies on the relationship between electric currents and magnetic fields. When an electric current passes through an electrical conductor, such as an electrically insulated copper or aluminum wire, it generates a magnetic field around the wire. This phenomenon, known as electromagnetism, was discovered by Hans Christian Ørsted. A single strand of wire carrying an electrical current produces a magnetic field that circles the wire, following Maxwell’s Right Hand Grip Rule. According to this rule, if you point your thumb in the direction of the current flow, your curled fingers show the direction of the magnetic field. To strengthen the magnetic field, the wire is often wound into a coil with many turns. Each loop of the coil adds to the magnetic field, making it stronger than that of a single straight wire. Placing an iron core inside the coil further amplifies the magnetic field. The iron core becomes magnetized when current flows through the coil, greatly increasing the overall magnetic strength.
This is because iron is a ferromagnetic material, meaning it easily becomes magnetized. The strength of electromagnets can be controlled in several ways, including increasing the current, adding more coils, and using a core material with higher magnetic permeability.