Lenz's law and instantaneous change in inductor's current

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SUMMARY

The discussion focuses on Lenz's law and the behavior of induced current in a coil when a magnet approaches and recedes from it. It establishes that as a magnet's north pole approaches a coil, the induced current generates a magnetic field that repels the magnet, while the receding magnet induces a current that attracts it. The participants clarify that the change in current direction is not instantaneous; rather, it transitions gradually as the magnet's velocity changes. A 180-degree phase difference between the magnet's movement and the induced current is confirmed as a key concept.

PREREQUISITES
  • Understanding of Lenz's law in electromagnetic induction
  • Basic knowledge of inductors and coils
  • Familiarity with magnetic fields and their interactions
  • Concept of phase difference in oscillatory systems
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  • Study the mathematical formulation of Lenz's law
  • Explore the concept of electromagnetic induction in AC circuits
  • Learn about the behavior of inductors in transient states
  • Investigate the principles of simple harmonic motion in electromagnetic systems
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Students of physics, electrical engineers, and anyone interested in understanding the principles of electromagnetic induction and the behavior of inductors in response to changing magnetic fields.

PainterGuy
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Hi,

I will use this text for my question: https://imagizer.imageshack.com/img921/1874/nUBPY6.jpg
Source: https://www.electrical4u.com/lenz-law-of-electromagnetic-induction/

The text says that when the north pole of a magnet approaches the coil, the induced current in coil is such that it creates a north pole to repel the approaching north pole of magnet. In other words, the coil resists the approach of magnet.

When the magnet's north pole starts receding from the coil, the induced current in coil is such that it creates a south pole to attract the receding north pole of magnet toward it. In other words, the coil resists the recession of magnet's north pole.

The following is my question statement. In an inductor or coil the current cannot change instantaneously. Therefore, as the magnet was approaching coil, it induced a current in the coil and this induced current generated its own magnetic field. So, when the magnetic starts receding away from coil, the current shouldn't switch its direction instantaneously. But the text suggests, or Lenz's law, as if the switch in direction of current is instantaneous. Where am I confusing it?

Thank you for your help!
 
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The linked text does not say things change instantaneously, and they don't.
Consider the magnet approaching the coil. For it to subsequently recede from the coil, its velocity towards the coil must continuously decrease from positive, through zero and become negative. As that happens, the current through the coil will likewise reduce to zero then grow in the opposite direction.

Hope that helps.
 
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Thank you, @andrewkirk .

I think that I understand it now. There is a 180 degrees phase difference between the magnet movement and induced current. I have assumed that the magnet follows simple harmonic motion and the system has been operating for some time. Please let me know if I have it correct. Thank you.
 

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Yes, given the additional assumption you state regarding the magnet's pattern of movement, that diagram agrees with my understanding of how the current reacts.
 
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