Lenz's Law: Understanding A-level Physics Problem

PatIn summary, Lenz's law states that an induced EMF will always act in a direction that opposes the change that caused it. However, in the case of a magnet falling through a coil with a gap in the circuit, there is still an EMF produced but no current. This can be explained by the fact that Lenz's law only applies to completed circuits, and without a complete circuit, the induced current cannot oppose the change. Therefore, the magnet's acceleration downwards remains unchanged.
  • #1
padraig
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Hi, I'm just doing my A-level physics revision and there's something I'm a bit unsure about. Lenz's law states that an induced EMF will always act to appose the change that is causing the EMF in the first place. However, if we take the example of a magnet falling through a coil that is part of a circuit which has a gap in it, then an EMF is still said to be produced but there is no current. The magent in this case falls to ground with unchanged acceleration g. Surely though, if Lenz's law holds true and it is the EMF that opposes changes, then the magnet's acceleration downwards would be decreased just as it would if the circuit was complete.

Any ideas would be of great help, thanks

Pat
 
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  • #2
padraig said:
Hi, I'm just doing my A-level physics revision and there's something I'm a bit unsure about. Lenz's law states that an induced EMF will always act to appose the change that is causing the EMF in the first place. Pat
That's a mis-statement of Lenz's law. The induced current will appear in such a direction that it opposes the change that produced it.
 

What is Lenz's Law?

Lenz's Law is a fundamental law in physics that describes the direction of induced current in a closed circuit. It states that the direction of the induced current will always be such that it opposes the change that caused it.

How does Lenz's Law relate to electromagnetic induction?

Lenz's Law is a direct consequence of Faraday's Law of electromagnetic induction. It explains the direction of the induced current in a closed circuit due to a changing magnetic field.

What are the practical applications of Lenz's Law?

Lenz's Law has numerous practical applications, such as in generators, transformers, and electric motors. It is also used to dampen induced currents in circuits and prevent damage to electrical equipment.

What is the mathematical representation of Lenz's Law?

The mathematical representation of Lenz's Law is given by the negative sign in Faraday's Law of electromagnetic induction. This means that the induced electromotive force (emf) is always opposite in direction to the change in magnetic flux.

How does Lenz's Law affect the motion of a conductor in a magnetic field?

According to Lenz's Law, the induced current in a conductor will create a magnetic field that opposes the change in magnetic flux. This will result in a force that acts on the conductor, causing it to experience a resistive force and slowing it down.

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