Can someone explain this to me? Thanks (1 Viewer)

[KONGYEWPENG1]

 

[DepressedPenguino]

Induction motorrr

 

[PhysicsMaths]

Induction motorrr

?

 

[PhysicsMaths]

Ok, let's look at one of the main postulates of Lenz's law;
Lenz's law states that an induced current produces a magnetic field that opposes the changing flux that created it in the first place.

Now, we will consider this case:
Consider a single point on that copper disc. As the magnet rotates, the point continually experiences an oscillation of magnetic field lines passing through that point, to no magnetic field lines passing through that point, so essentially, it is constantly experiencing a changing flux. Relating this to Lenz's law, a current is induced within the copper disc to oppose this change, that is, the induced eddy currents will interact with the external magnetic field to experience a torque to "catch up" to the magnet and hence flow in the same direction as the magnets rotation to ensure that there is minimal change in flux.

(might be wrong)

 

[jkerr138]

Yes, I would say this concept refers to an AC Induction Motor.
My reasoning for the answer C:
As Copper is a non-ferrous material, the changing magnetic field produced by the bar magnet, induces a magnetic field within the copper disc. As a result of our knowledge of Faraday's Law, a current is also induced, and Lenz's Law opposes this through the production of Eddy Currents (Induced Current) which moves the copper disc in the direction of the curved magnetic path (bar magnet).
From our knowledge of an AC Induction Motor, we require an alternating/changing magnetic field to induce a magnet field followed by the production of a current.
Hopefully this can help you.

 

[PhysicsMaths]

Yes, I would say this concept refers to an AC Induction Motor.
My reasoning for the answer C:
As Copper is a non-ferrous material, the changing magnetic field produced by the bar magnet, induces a magnetic field within the copper disc. As a result of our knowledge of Faraday's Law, a current is also induced, and Lenz's Law opposes this through the production of Eddy Currents (Induced Current) which moves the copper disc in the direction of the curved magnetic path (bar magnet).
From our knowledge of an AC Induction Motor, we require an alternating/changing magnetic field to induce a magnet field followed by the production of a current.
Hopefully this can help you.

Yes, but can you explain why it's anti-clockwise and not clockwise?

 

[Kaido]

Yes, I would say this concept refers to an AC Induction Motor.
My reasoning for the answer C:
As Copper is a non-ferrous material, the changing magnetic field produced by the bar magnet, induces a magnetic field within the copper disc. As a result of our knowledge of Faraday's Law, a current is also induced, and Lenz's Law opposes this through the production of Eddy Currents (Induced Current) which moves the copper disc in the direction of the curved magnetic path (bar magnet).
From our knowledge of an AC Induction Motor, we require an alternating/changing magnetic field to induce a magnet field followed by the production of a current.
Hopefully this can help you.

Explanation is a little bit dodgy, not exactly correct.

This question is a simple application of Lenz's law and the Right/Left hand grip rule to determine the direction of motion

 

[PhysicsMaths]

Explanation is a little bit dodgy, not exactly correct.

This question is a simple application of Lenz's law and the Right/Left hand grip rule to determine the direction of motion

Could you please provide some insight into how to use RHG rule to solve this q?

 

[anomalousdecay]

Ok think of it this way.

By Lenz's Law, the disc will try to oppose a change in flux. By doing so, it will produce eddy currents to oppose the change in flux. So the change in flux is characteristic by a magnet rotating here.

So what will the disc do? It will oppose this flux by trying to "push" the magnet away from it. How will it do this? The eddy currents will be induced such that the disc will have a "north pole" characteristic in the direction of the magnet (to try and prevent the magnet from producing a change in flux in the disc). Similarly, the same thing will happen near the south pole of the magnet and disc.

Hence, with a torque being applied to the magnet itself, this magnet will also produce a torque on the disc so that the disc rotates in the same direction as the magnet.

Is this clear concept wise?

 

[sy37]

C because Lenz' law = oppose change, will do this by way of reducing the relative motion between the two components ie same direction