Context:
The Hindu| Science article dated 18th June 2024
Electromagnets:
Invented in 1824 by British physicist William Sturgeon, electromagnets are integral to modern technology. They are utilized in various applications such as loudspeakers, motors, magnetic resonance imaging (MRI) machines, maglev trains, and particle accelerators.
Working Principle of Electromagnets
- Electric Current and Magnetic Field:
- An electric current flowing through a wire creates a magnetic field around the wire.
- Increasing the current flowing through the coil increases strength of magnetic field produced.
- Coiling the wire concentrates the magnetic field within the coil.
- Core Material:
- Wrapping the wire around a magnetic material, known as the core, amplifies the magnetic field.
- Ferromagnetic metals like iron have small magnetic fields produced by their atoms, which usually point in random directions and cancel each other out.
- Alignment of Magnetic Domains:
- When an electric current flows through the coil wrapped around a ferromagnetic core, the produced magnetic field penetrates the core.
- This external magnetic field aligns the tiny magnetic fields (domains) within the iron.
- The alignment of these domains strengthens the overall magnetic field.
Types of Electromagnets
- Continuous Magnetic Field Production:
- A magnetic field is produced as long as current flows through the coil.
- Certain core materials remain weakly magnetized even after the current is switched off.
- Superconducting Electromagnets:
- Superconducting wire coiled around a core can produce magnetic fields up to 30 tesla (600,000 times as powerful as the Earth’s magnetic field).
- Used in applications such as MRI machines.
- Bitter Electromagnets:
- Current flows through wires coiled in a helical stack of electromagnets.
- These can produce magnetic fields up to 40 tesla.
Applications of Electromagnets:
- Transportation: Maglev trains use electromagnets to levitate and propel themselves.
- Entertainment: Speakers convert electrical signals to sound waves using electromagnets.
- Medical Technology: MRI machines use strong electromagnets to image the human body.
- Industry: Electromagnets help separate scrap metal by picking up ferrous metals. They are also crucial in electric motors, converting electricity into motion.
Previous Year Question
With reference to “Blockchain Technology”, consider the following statements:
1. It is a public ledger that everyone can inspect, but which no single user controls.
2. The structure and design of blockchain is such that all the data in it are about cryptocurrency only.
3. Applications that depend on basic features of blockchain can be developed without anybody’s permission.
[UPSC Civil Services Exam – 2014 Prelims]
Which of the statements given above is/are correct?
(a) 1 only
(b) 1 and 2 only
(c) 2 only
(d) 1 and 3 only
Answer: (a)
Expalanation:
Statement 2 is not correct:
Blockchain operates through a decentralized platform requiring no central supervision, it is used in voting, banking, messaging app, internet advertising, etc. Hence, it is not restricted to cryptocurrency.
