What is the direction of the magnetic force on a wire between two magnets?

In summary, the diagram shows a wire carrying a current of electrons out of the page between the poles of a permanent magnet. The direction of the magnetic force exerted on the wire is down, as determined by the Lorentz equation, due to the negatively charged electrons moving in the direction out of the page and the magnetic field being in the direction from the north pole to the south pole. The direction of the force can also be determined using the right hand rule.
  • #1
Matt H
7
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The diagram shows a straight wire carrying a flow of electrons out of the page. The wire is between the poles of the permanent magnet. The direction of the magnetic force exerted on the wire is:


phys.jpg



Please Note: My diagram isn't perfect but both magnets are the same size and the wire is equidistant from both of the magnets.



A) Out of the page


B) <---


C) --->


D) up arrow


E) down arrow


An explanation is much more important to me than the correct answer (i have an answer key).
 
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  • #2
Matt H said:
The diagram shows a straight wire carrying a flow of electrons out of the page. The wire is between the poles of the permanent magnet. The direction of the magnetic force exerted on the wire is:

Please Note: My diagram isn't perfect but both magnets are the same size and the wire is equidistant from both of the magnets.

An explanation is much more important to me than the correct answer (i have an answer key).

So how does a wire experience a force? Well, it does it because the current is comprised of electrons (charged particles) moving inside the wire. If those moving charged particles are going through a magnetic field they can experience a force given by the Lorentz equation.

That is F = q V x B.

So let's put it all together. First question. In what direction is the magnetic field? Easy. Magnetic fields are defined to be in the direction from the north pole to the south pole. Hence it is to the right. What direction is the velocity of the charged particles? Well those are given as out of the paper. Thus, what direction is the vector quantity V x B? Well if you take your right hand with thumb up, first finger forward and second finger bent at 90 degrees to the first, the right hand rule is First finger in direction of V, second finger in direction of B and thumb shows direction of result which is up. So it looks like our force is up. But wait! See that q in the equation? That is the charge of the particle. For an electron the value is -e. And that minus sign reverses our result making the force on the wire DOWN. OK? Does that agree with the key?
 

1. How does a wire between two magnets affect the magnetic field?

The wire between two magnets can alter the magnetic field in two ways. First, it can redirect the magnetic field lines, causing them to bend and flow through the wire. Second, the wire itself can become magnetized and create its own magnetic field. This phenomenon is known as electromagnetism.

2. Can the wire between two magnets generate electricity?

Yes, the wire between two magnets can generate electricity through electromagnetic induction. When the wire moves relative to the magnets or the magnets move relative to the wire, a changing magnetic field is created, which induces an electric current in the wire.

3. How does the distance between the magnets affect the wire?

The distance between the magnets can affect the wire in two ways. First, a larger distance between the magnets will result in a weaker magnetic field, leading to a weaker effect on the wire. Second, a larger distance will also increase the resistance of the wire, making it more difficult for electricity to flow through it.

4. Can a wire between two magnets be used to lift objects?

Yes, a wire between two magnets can be used to create an electromagnet that can lift objects. By passing electric current through the wire, the magnetic field is strengthened, allowing it to attract and lift objects made of materials such as iron or steel.

5. Are there any safety precautions to consider when using a wire between two magnets?

Yes, there are some safety precautions to consider when using a wire between two magnets. The wire may become hot when electricity is passed through it, so it is important to handle it with caution. Also, strong magnets can be dangerous if handled improperly, so it is important to follow proper safety protocols when working with them.

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