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Current coil is a wire wrapped around an electrical conductor. It illustrates the phenomenon of electromagnetism. Electricity and magnetism are theoretically separate forces. In 1905 Albert Einstein’s special theory of relativity established that both these aspects are of one common phenomenon called electromagnetism. The current coil is the best means to understand this phenomenon.
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Key Takeaways: Electromagnetism, Magnetism, Magnet, Conductor, Electrical conductor, Electricity, Current coil, Magnetic Field, Phenomenon
Current Coil
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A current coil is a coil of a wire wrapped around an electrical conductor. Here the wire is generally an insulated copper wire. The conductor is a soft iron core. The current coil conductor experiment is used to prove the phenomenon of electromagnetism.
Current Coil
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Electromagnetism
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When electricity is let to pass through the copper coil wrapped around the iron conductor, it behaves like a magnet. This phenomenon is called electromagnetism. As the electrical current moves around the loops of the coil, it generates a magnetic field like that of a small bar magnet. It has a north pole on one side and the south pole on the opposite side.
Electromagnet
When iron nails are put near an iron conductor coiled around a current-carrying copper wire, the nails get attracted towards the coil.
Read More: Magnetic effects of electric current
Factors for Electromagnetism
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Number of loops: With the increase in the number of turns, there is an increase in current in amperes and magnetic field. It depends on the thickness of the wire also.
Battery current: Battery current is the strength of the current flowing through the conductor. The greater the electric current, the greater the strength of the current coil.
Factors that affect electromagnetism
Metal Core: The material in the conductor. Mostly ferrous or iron-bearing material is used to improve electromagnetism. Aluminium-nickel-cobalt alloy will produce a strong magnetic field. Iron cores create very strong magnetic fields. Steel cores create weaker magnetic fields. Neodymium cores create the strongest electromagnetic fields. Taking out the core slightly out of the coil will weaken the field.
Temperature: Low temperature improves the electric current-carrying ability. For instance, the strongest electromagnets are made of superconductors cooled with liquefied nitrogen or helium.
Also Read:
Applications of Current Coil
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There are various applications of the current coil. They are used in actuators such as valves, electric bells, buzzers, loudspeakers, headphones, MRI machines, relays, transformers, magnetic recording and data storage equipment like tape recorders, VCRs, hard disks. The other applications are as follows:
- An electromagnet can be turned on and turned off as per the need, unlike that of a regular permanent magnet.
- Current coils are used as can crushers. It works on the influence of the electromagnetic field. The more electromagnetic field is generated when a can is placed inside a coil. The coil gets energized to bend and deform the can into a flat disc.
- Current coils are generally used as electromagnets. The electromagnets are of different types like degaussing coil, Maxwell coil, solenoid coil, voice coil, etc
- Current coils are used in making magnetic cranes. In landfills, huge metal scrap can easily be clung to the energized electromagnet and can be unloaded on the other side when it is de-energized.
Electromagnetic Cranes
Read More: Electromagnetic field
Things to Remember
- An integrated phenomenon of electricity and magnetism is called electromagnetism.
- A current coil is a coil of a wire wrapped around an electrical conductor.
- Number of loops in the current coil, the strength of the electric current, conductor metal and temperature influence the strength of the electromagnetic field.
- Current coils are used in actuators such as valves, electric bells, buzzers, loudspeakers, headphones, MRI machines, relays, transformers, magnetic recording and data storage equipment like tape recorders, VCRs, hard disks.
- An electromagnet can be turned on and turned off as per the need, unlike that of a regular permanent magnet.
- Current coils are used as magnetic cranes, can crushers and electromagnets.
- The electromagnets are of different types like degaussing coil, Maxwell coil, solenoid coil, voice coil, etc.
Read More: Permanent Magnets and Electromagnets
Previous Year Questions
- An electron in motion is associated with… [ KCET 1996]
- Two parallel wires carry electric current in same direction. The wires... [ KCET 1996]
- Resistance of an ideal ammeter is...[ KCET 1996]
- If a current of 0.1 A is passed through the coil, what is the couple acting?...[CBSE Class 12 ]
- The acceleration of the falling magnet is..[NEET]
- A bar magnet is equivalent to ............[KCET 2004]
- A metal ring is held horizontally and bar magnet is dropped through….[NEET]
- The total charge, induced in a conducting loop when it is moved in magnetic field depend on...[NEET 1992]
- If a charge particle enters perpendicular in the uniform magnetic field, then...[JIPMER 2016]
- Who invented the cyclotron?
- When a charged particle moving with velocity is….
- The angle of dip at a place is….
- The associated magnetic moment is given by….
- A uniform electric field and a uniform magnetic field are produced…
- Ampere’s circuital law can be derived from…..
- If a magnetic dipole of moment M situated in the direction of …
- If the susceptibility of dia, para and ferro magnetic materials are ….
- Materials suitable for permanent magnet, must have which of the following properties ?
- At what temperature, the ferromagnetic substances become paramagnetic ?
- a magnetic induction of strength at its centre is...
Sample Questions
Ques: How can you prove that a current coil behaves like a magnet? (2 marks)
Ans: It is proved by using a 9V battery, copper wires, iron rod and some iron nails. When iron nails are put near an iron conductor coiled around a current-carrying copper wire, the nails start to attract and stick to the coil.
Ques: What is a solenoid? How does it behave? What is its main use? (2 marks)
Ans: A copper coil of many circulars turns around a cylindrical insulating body such that its length is greater than its diameter is called a solenoid. When current is passed through a solenoid, magnetic field line patterns occur that are those of a bar magnet. A solenoid is used to make both a temporary magnet called an electromagnet and a permanent magnet.
Solenoid
Ques: How does a current coil produce an electromagnetic field? (2 marks)
Ans: When electricity is let to pass through the copper coil wrapped around the iron conductor, it behaves like a magnet. This phenomenon is called electromagnetism. As the electrical current moves around the loops of the coil, it generates a magnetic field like that of a small bar magnet. It has a north pole on one side and the south pole on the opposite side.
Ques: What are the four important factors that influence the electromagnetic field produced by a current coil? (3 marks)
Ans: Four important factors influence the electromagnetic field produced by a current coil as follows:
- Number of loops: With the increase in the number of turns, there is an increase in current in amperes and magnetic field.
- Battery current: The strength of the current flowing through the conductor influences the strength of the magnetic field.
- Metal Core: The material with which the conductor is made influences the magnetic field.
- Temperature: Low temperature improves the electric current-carrying ability.
Ques: What are the different metals used in making electromagnets? (2 marks)
Ans: Mostly ferrous materials are used in making electromagnets. Aluminum-nickel-cobalt alloy will produce a strong magnetic field. Iron cores create very strong magnetic fields. Steel cores create weaker magnetic fields. Neodymium cores create the strongest electromagnetic fields.
Ques: What are the different uses of the current coil in daily life? (2 marks)
Ans: The current coil has many uses in day-to-day life. It is generally used to make electromagnets. An electromagnet can be turned on and turned off as per the need, unlike that of a regular permanent magnet. It is used in making actuators such as valves, electric bells and buzzers, loudspeakers and headphones, MRI machines, relays, transformers, and magnetic recording and data storage equipment like tape recorders, VCRs, hard disks. Current coils are used in making magnetic cranes. In landfills, huge metal scrap can easily be clung to the energised electromagnet and can be loaded on the other side when it is de-energized.
Ques. State Faraday’s Law of Electromagnetic Induction. (3marks)
Ans. First Law: Whenever magnetic flux linked with the closed loop or circuit changes, an emf is induced in the loop or circuit which lasts as long as the change in flux is continuous.
Second Law: The induced emf in a closed loop or circuit is directly proportional to the rate of change of magnetic flux linked with the closed loop or circuit.
where,
N = number of turns in loop.
Negative sign indicates Lenz’s law.
Ques. State Fleming’s Right-Hand Rule. (2 marks)
Ans. If the thumb, forefinger and middle finger of the right hand are stretched mutually perpendicular to each other such that the forefinger points the direction of a magnetic field, the thumb points towards the direction of magnetic force, then the middle finger points towards the direction of induced current in the conductor.
Ques. What are the ways by which induced emf can be produced in a coil? (2 marks)
Ans.
- Putting the coil/loop/circuit in a varying magnetic field.
- Changing the area A of the coil inside the magnetic field.
- Changing the angle 0 between B and A.
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