All About Electromagnets
The magnetic effects of an electric current were first discovered in 1820 by Danish scientist, “Hans Christian Oersted”. A few years later, British scientist William Sturgeon invented the first electromagnet in 1824. It has around 18 turns of bare copper wire wrapped over horseshoe-shaped piece of iron. Electromagnetism has created a revolution not only in the field of engineering but also in various other fields like medicine, space, construction etc. Here in this article, we will discuss the important facts about electromagnets, its differences with permanent magnets and important applications in our everyday life.
Differences between a Permanent Magnet and an Electromagnet:
- The strength of a Permanent Magnet cannot be changed. However, the strength of an Electromagnetic waves can be changed and are even capable of producing very strong magnetic fields.
- The polarity of an electromagnet can be altered by simply changing the direction of current electricity. However, the polarity of a Permanent Magnet polarity cannot be altered.
- Electromagnets are temporary as they exhibit magnetic fields only when the electric current flows through it. Whereas, a permanent magnet uses the natural magnetism of certain materials (typically ones that display Ferromagnetism) to create permanent magnetic fields.
How to make an electromagnet?
To make a simple electromagnet, wrap coils of wire (usually insulated copper wire) around a ferromagnetic core (mostly iron). Ferromagnetic materials like cobalt, nickel, iron, etc have an excellent property of concentrating magnetic fields through them, making the field strength higher. On passing the electric current through the coil, a magnetic field is developed around it, which is caught in the ferromagnetic core. One end of your electromagnet will behave as the north pole and the other end will behave as the south pole. On reversing the direction of current, the poles of an electromagnet will also get reversed. On disconnecting the current supply, the core will lose its magnetism.
How to enhance the power of an Electromagnet?
- The strength of an electromagnet can be increased by simply adding more number of turns to the coil. However, its strength gets reduced if the distance of coil from its core increases.
- The strength of an electromagnet can also be enhanced by increasing the strength of current passing through the wire. However, due to overheating, excess supply of current could be dangerous and can cause potential damage to the circuit components.
- The thickness and the type of material used in making the core of an electromagnet plays an important role in making an electromagnet more powerful. The selection of material can be done with the help of a permanent magnet. If the material used in making the core of an electromagnet is not attracted by a permanent magnet (For Example, an Aluminium bar) then it will never make a strong electromagnet.
Applications of an Electromagnet:
Nowadays, the electromagnets are used almost everywhere. Electric motors, speakers, microwave ovens, modern day power door locks, electric fans, automobiles, etc are some of the devices that have electromagnetic principle involved in their functioning.
The loudspeakers used for public announcements or for transmitting messages over a long distance is a perfect example of an electromagnetic appliance. The coil moves under the electromagnetic force producing loud sound waves that are transmitted over a very long distance. Similarly, When a doorbell button is pressed, the coil gets energized, and due to the electromagnetic forces, the bell sounds. Electromagnets are extensively used in nuclear physics to steer the position and speed of the electron beam.
The electromagnets can be energized and de-energized as per our requirements. This principle is used for separating heavy metal objects in the scrap yard. Electromagnets are energized by supplying power to the electric circuit. Thus, the electromagnet attracts scrap metal objects like junk cars present in the scrap yard and carries them to any designated section. After the scrap is located in the desired location, the scrap metal is detached from the electromagnet by disconnecting the power supply (de-energized).
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