Very basic electromagnet vs permanent magnet question

In summary, the conversation discusses the confusion surrounding the direction of current in a circuit when an electromagnet is switched on. The individual believes that the current should go from X to Y to oppose the electromagnet, but their textbook states that it goes from Y to X. They seek clarification on whether the electromagnet is equivalent to pushing a permanent magnet to the left or right. It is concluded that the book is incorrect and the current would need to go from X to Y to counter the change in the magnet coil.
  • #1
MironeDagains
23
0
When you switch on an electromagnet (who's north pole is pointing to the left), is it the same thing as if you had pushed a permanent magnet to the left? Or to the right? I believe it's to the left. But apparently my textbook thinks it's to the right. Who's correct?

Why I'm asking:I've attached an image of the question that is confusing me. It is to my understanding that when you push a permanent magnet through a circuit, the circuit's induced magnetic field will try and oppose the movement of the permanent magnet and so the current within the circuit will go anticlockwise (if you're looking at it from the magnet's point of view as it's pushed through it), that's exactly what my textbook said on an earlier page.

Problem?:However, in this question, the electromagnet (to the left of the circuit) is switched on and so is that the same as pushing a permanent magnet to the left? Or to the right? Because if it's to the left, as I believe it is, then the induced magnet created by the circuit should be opposing this electromagnet and the only way it could do that is if the current was going from X to Y...but the book says that the current is going from Y to X..which makes absolutely no sense because then the induced magnetic field in the circuit will be going the same direction as the electromagnet and that is a big nono!Please help me as this has stumped both me and my dad (who did physics in high school and was top of his class...35 years ago)
 

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  • #2
Where does your textbook compare switching the electromagnet with moving a magnet?
I don't think that is a useful model. You change the field strength at some places, but this change happens due to effects you want to neglect in this analysis (field lines not aligned with the long axis).
 
  • #3
MironeDagains said:
and the only way it could do that is if the current was going from X to Y...but the book says that the current is going from Y to X.
You are right. Your book is wrong.

Of course the induced current will have to circulate the counter way around, as to the current change in the magnet coil.
 
  • #4
See Lenz's Law.
 

Related to Very basic electromagnet vs permanent magnet question

1. What is the difference between an electromagnet and a permanent magnet?

An electromagnet is a magnet that is created by running an electric current through a wire, while a permanent magnet is a magnet that is naturally magnetized and does not require an electric current to maintain its magnetic field.

2. How does an electromagnet work?

An electromagnet works by using the flow of electrons through a wire to create a magnetic field. The strength of the magnetic field can be increased or decreased by adjusting the amount of current flowing through the wire.

3. What are some practical applications of electromagnets?

Electromagnets are used in a variety of everyday items, such as doorbells, speakers, and electric motors. They are also used in more advanced applications, such as MRI machines and particle accelerators.

4. Can an electromagnet be turned off?

Yes, an electromagnet can be turned off by stopping the flow of electricity through the wire. This is one of the main differences between an electromagnet and a permanent magnet. A permanent magnet cannot be turned off.

5. Which is stronger, an electromagnet or a permanent magnet?

It depends on the strength of the electric current flowing through the wire. An electromagnet can be made to be much stronger than a permanent magnet, but it requires a constant flow of electricity to maintain its strength. A permanent magnet, on the other hand, will maintain its strength without the need for an external power source.

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