What are Electromagnets: Definition & Working

Electromagnets are magnets that are powered by electricity. The electromagnet was developed first in the year 1824 by British scientist William Sturgeon, who used a painted horseshoe-shaped iron piece wrapped in bare copper wire.

Unlike a permanent magnet, the strength of an electromagnet can be modified by altering the amount of electric current flowing through it. Magnetism is lost when the flow of current is interrupted. Electric current has the capability to generate a magnetic field in a plane perpendicular to the current flow’s direction. Electromagnets generally use this principle.

An electromagnet can be expressed as a magnet that is known to function on electricity. Unlike a permanent magnet, an electromagnet’s strength can be altered by changing the amount of electric current flowing via it. In case the current flow is cut, the property of magnetism stops existing.

Read More: Permanent Magnets and Electromagnets

Key Terms: Electromagnetism, Electric Current, Magnetic Flux, Ferromagnetic, Circuits, Electromagnets, Electric Field, Magnetic field

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What are Electromagnets?

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Electromagnet is made of a wire twisted in a coil, creating a magnetic field because of the current flowing through the wire and coil's core. The magnetic field disappears as soon as the current is turned off. An electromagnet can be represented as a magnet which is known to function on electricity.

Electromagnet

The magnetic core around the coil of wire is made of ferromagnetic material, such as iron. The magnetic flux is strengthened by the magnetic core, which results in more powerful magnets. An electromagnet functions when the electric current causes a magnetic field to form a circle around the current.

Properties of Magnet

Out of the many properties of magnets, a few are as mentioned below:

• Attractive Property: Ferromagnetic materials, such as iron and nickel, have attractive properties. Meaning that they are attracted by magnets.
• Repulsive Property: In magnets, the like poles repel one another, whereas the unlike poles attract each other.
• Directive Property: A freely suspended magnet is seen to point in the north-south direction.

Read More: Inductance formula

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History of Electromagnets

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Electromagnets produce electromagnetic fields and function on the principles of electromagnetism. Electromagnetic fields are the result of the interaction of two fields: electric and magnetic fields. Hans Christian Oersted, a Danish physicist, proved in 1820 that when current travels via a wire, a nearby compass needle deflects. 

Horseshoe Magnet

The electromagnet was designed in 1824 by British scientist William Sturgeon, who used a painted horseshoe-shaped iron piece wrapped in bare copper wire. Sturgeon further demonstrated the electromagnet's strength by lifting other iron fragments. Joseph Henry, a US physicist, developed a more advanced electromagnet in 1830 and popularised it.

Read More: Rare Earth Magnets

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Making of Electromagnet

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The formation of an Electromagnet can be achieved by:

• When charged particles such as protons and electrons remain stationary, electric forces such as attraction or repulsive forces are formed between them.
• Due to their mobility, they create magnetic forces that either repulse or attract charged particles.
• A magnet's magnetic field is generated by many particles travelling within the magnet. 

Formation of Electromagnets

• Electromagnets are often manufactured out of a wire that has been twisted into a sequence of twists.
• A conventional magnet is wrapped around the wire turns.
• The electromagnet is stronger since it is constructed of ferromagnetic material like iron.

The electromagnet can be strengthened using the following ways.

• Draping the coil around a piece of iron (such as an iron nail).
• Increasing the coil's number of turns.
• Increasing the amount of current that passes through the coil.

Read More: Eddy Currents

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Working of Electromagnet

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The working principle of an electromagnet is:

• Individual magnetic fields cancel each other out when the atoms in the nail are orientated in arbitrary ways.
• Under the influence of electric current, these atoms are reoriented to point in the same direction.
• These different magnetic fields merge to form a powerful magnetic field. 
• The reorientation degree rises as the current flow increases, resulting in a greater magnetic field.
• Increased current flow has no effect on the magnetic field created until all the particles are reoriented correctly in the same direction.
• The magnet is saturated at this stage.

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Applications of Electromagnets

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The primary functioning concept of most electric equipment in the house is the electromagnetic principle.

• An electric fan, electric doorbell, induction stove, magnetic locks, and other electromagnet applications in the house are only a few examples. Electromagnetic induction keeps the motor spinning in an electric fan, which causes the blades to revolve. When the button of an electric doorbell is pressed, the coil is charged by electromagnetic forces, and the bell sounds.
• Cell phones and telephones we used to make long-distance calls could not have existed without electromagnets. Mobile phones and cell phones are useful due to electromagnetic pulses and signal interaction.
• Data is saved in the electromagnetic format in the form of bytes and bits in e-book devices and phones. A magnetic tape, included in the computer hardware, works on electromagnetism. Electromagnets played a significant part in the data storage of VCP and VCR in the past.
• Electromagnets are also used in medicinal applications. The MRI scan, which stands for Magnetic Resonance Imaging, is an electromagnet-based instrument. With the use of electromagnetism, the gadget can scan all the minute features of the human body.

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Advantages and Disadvantages of Electromagnets

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Electromagnets have both benefits and disadvantages when compared to permanent magnets. They are superior in certain regions, whereas permanent magnets are better in others. Electromagnets have proven to be advantageous over permanent magnets in many aspects.

Advantages of Electromagnets

Some of the major advantages of Electromagnets are:

• ​Electromagnets are not permanent magnets.
• The magnetic strength of Electromagnets can be both increased or decreased. 
• Electromagnets typically tend to have higher magnetic power than permanent magnets.

Disadvantages of Electromagnets

Some of the major disadvantages of Electromagnets are:

• One of the downsides of electromagnets is that they heat up quickly, resulting in a significant loss of electrical energy owing to heat creation. A steady magnetic field is required for a continuous power supply.
• A considerable amount of area is required to maintain a high magnetic field with a significant number of coils of copper wires. As a result, electromagnets are unsuitable for use in compact places.
• Electromagnets are prone to short-circuit because of magnetic fields produced by an electric current which can also injure the user.

Read Also:

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Things to Remember

• An electromagnet can be expressed as a magnet that functions on electricity. It is constructed of a coil of wire (i.e., wire curled in series). 
• Particle Accelerators, Amplifiers, Magnetic Separation, Electric Motors and Generators, MRI machines, Control Switches in Relays, and Hard Drives are just a few examples of electromagnet applications.
• An electromagnet’s poles can be reversed by means of reversing the flow of electricity.
• An electromagnet can be strengthened by draping the coil around a piece of iron (like, iron nail).

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Previous Year Questions

Questions on Lenz Law :

1. Lenz’s law is consequence of the law] of conservation of….. [UPSEE 2019]
2. The magnetic field is increasing at a constant rate. The directions of induced current in wires AB and CD  are…. [VITEEE 2019]
3. the circular loop of wire is moved with velocity towards the infinite current carrying wire…… [VITEEE 2016]
4. Two identical coaxial coils P and Q  carrying equal amount of current in the same direction are  ...[KEAM]
5. The polarity of induced emf is given by….[KEAM]

Questions on Electromagnetic Induction:

1.  If a transformer of an audio amplifier has output impedance 8000 0 and the speaker has input impedance…...[JCECE 2005]
2. A conducting loop in the shape of a right angled isosceles triangle of  …..[JEE Advance 2016]
3. A 10m long horizontal wire extends from North East to South West. It is falling with a speed of 5.0ms⁻¹……. [ JEE Main 2019]
4. According to Lenz's law of electromagnetic induction … [JKCET 2008]
5. An electric bulb is rated at … [JKCET 2006]

Question on Transformers:

1. The output of a step down transformer is measured to…..[KCET 2017]
2. The core of a transformer is laminated to reduce….[KCET 2001]

Questions on Eddy Currents :

1. The working of magnetic braking of trains is based on….[KCET 2018]
2. Induction furnace uses ______ to produce heat…. [JIPMER 2019]

Questions on Faradays laws of induction:

1. Two identical circular coils A and B are kept on a horizontal tube side by side without touching each other…. [KCET 2013]
2. The magnetic flux through a circuit of resistance RR changes by an amount….[NEET 2004]

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