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What is an Electromagnet?


From UPSC perspective, the following things are important :

Prelims level: Electromagnetism, Faraday and his contributions

PC: The Hindu

Why in the News?

Recently Scientists have designed a magnetic resonance imaging (MRI) scanner that costs a fraction of existing machines, setting the stage for improving access to this widely used diagnostic tool. So we need to know about the Electromagnet.

What is an Electromagnet?

  • Invented in 1824 by William Sturgeon, electromagnets revolutionised technology.
  • Sturgeon was an English physicist and inventor who discovered that wrapping a coil of wire around a piece of iron and passing an electric current through the wire produced a magnetic field.
  • Electromagnets are used in Loudspeakers for sound reproduction, Motors for mechanical movement., and MRI machines for medical imaging, etc

How Electromagnets Work?

  • Electric current flowing through a wire generates a magnetic field around the wire.
  • Coiling the wire enhances this magnetic field by concentrating it within the coil’s core.
  • This configuration creates an electromagnet, where the strength of the magnetic field is directly proportional to the current flowing through the coil.
  • The magnetic flux density so generated is measured in ‘Tesla’.

Enhancing Magnetic Strength with a Core

  • Coiling the wire around a magnetic material (core), such as iron or steel:
    • Amplifies the magnetic field produced by the electric current.
    • Ferromagnetic materials like iron align their internal magnetic domains with the external magnetic field generated by the coil.
    • This alignment significantly increases the overall magnetic strength of the electromagnet compared to a non-magnetic core.

Persistence of Magnetization

  • It refers to the property of a material to retain a certain amount of magnetization even after the removal of an external magnetic field.
  • Certain core materials exhibit retained magnetization even after the current ceases.
  • This residual magnetism is useful in applications requiring sustained magnetic fields, such as:
    • Superconducting electromagnets used in MRI machines, are capable of producing magnetic fields up to 30 Tesla.
    • Research electromagnets like those used in particle physics, which require stable and powerful magnetic fields.

Who was Michael Faraday (1791-1867)?

  • Michael Faraday was a pioneering English scientist and physicist who made substantial contributions to the fields of electromagnetism and electrochemistry.
  • Faraday is best known for his experiments and discoveries in electromagnetism, which laid the groundwork for the principles of electromagnetic induction and the laws of electrolysis.

Key achievements of Michael Faraday include:

  1. Electromagnetic Induction: He discovered electromagnetic induction in 1831, showing that a changing magnetic field induces an electric current in a nearby conductor.
  2. Electrochemistry: Faraday formulated the laws of electrolysis, which describe the quantitative relationship between the amount of material produced or consumed during electrolysis and the amount of electricity passed through the electrolyte.
  3. Faraday’s Laws of Electromagnetic Induction: These laws describe the fundamental principles of generating electricity using magnetic fields, forming the basis for the development of electric generators and transformers.
  4. Faraday Cage: He invented the Faraday cage, a device used to block electromagnetic fields.



[2011] Microbial fuel cells are considered a source of sustainable energy. Why?

  1. They use living organisms as catalysts to generate electricity from certain substrates.
  2. They use a variety of inorganic materials as substrates.
  3. They can be installed in wastewater treatment plants to cleanse water and produce electricity.

Which of the statements given above is/are correct?

(a) 1 only

(b) 2 and 3 only

(c) 1 and 3 only

(d) 1, 2 and 3

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