We already know that an electric current has the ability to produce magnetic field in a plane perpendicular to the direction of current flow. The electromagnet uses this principle. Simply put, an electromagnet is a magnet which functions on electricity. If the current flow is cut, the property of magnetism ceases to exist.
But this is also an advantage of the electromagnet over a permanent magnet because controlling the electric current also controls the magnetic field in this case i.e., the strength of electric field controls the strength of magnetic field also. In fact, the poles of an electromagnet can even be reversed by reversing the flow of electricity.
Electromagnets are made out of a coil of wire (wire curled in series). This is more effective in producing a magnetic field than just a wire running straight. This effect can be strengthened by winding a wire tightly around a powerful core, made of magnetic material, such as iron. The picture above shows a coil wound around an iron nail. On its own the iron nail is not magnetic.
So how does this work? Let’s consider the iron nail itself. Why does it not produce a magnetic field when not influenced by an electric field? What changes?
Normally, the atoms in the nail are oriented in random directions and individual magnetic fields cancel each other out. Under the influence of electric current, these atoms are reoriented to start pointing in the same direction. All these individual magnetic fields together create a strong magnetic field. As the current flow increases, this degree of reorientation also increases, resulting in a stronger magnetic field. Once all the particles are reoriented perfectly in the same direction, increasing current flow will not affect the magnetic field produced. At this point, the magnet is said to be saturated.
Uses of Electromagnets
- Particle Accelerators
- Magnetic Separation
- Electric Motors and Generators
- MRI machines
- Control Switches in Relays
- Spacecraft Propulsion Systems
- Induction Heating
- Hard Drives
Electromagnetism is one of the fundamental phenomenon in nature. But why do we study electricity and magnetism separately? Learn Physics the right way with BYJU’S.