# Repelling a very weak permanent magnet with an electromagnet

• EddieP
In summary, the conversation is about using an electromagnet to repel a permanent magnet that is axially magnetized and placed on top of an iron core. The question is whether the electromagnet will have trouble repelling the permanent magnet if its magnetic field is weak. The answer is that assuming the electromagnet is always strong enough, the strength of the permanent magnet's magnetic field does not play a role and it will still be repelled. However, there is a possibility that a very weak permanent magnet may not be repelled at all and act like a piece of metal. This topic is related to solenoid valves, which can be found on a Wikipedia page.
EddieP
I have a question about magnetic repulsion. Suppose I have a permanent magnet (axially magnetized) placed on top of the iron core of an electromagnet. I want to switch on the elctromagnet to repel the permanent magnet. (Please assume the permanent magnet is contained in some kind of tube that allows up and down movement but prevents it from spinning around. Please also assume that the electromagnet always produces a field strong enough to repel the permanent magnet - whatever that may be)
If the permanent magnet's magnetic field is very weak, will the electromagnet have trouble repelling it?
I know that if the electromagnet were attracting the permanent magnet, the only thing that would matter would be the strength of the electromagnet. What about repelling the permanent magnet? Assuming the electromagnet is always strong enough, does the magnetic field of the permanent magnet play any role? Is there a chance that an extremely weak magnet would simply act as a piece of ferrous metal and not be repelled by the electromagnet at all?

## 1. How does an electromagnet repel a permanent magnet?

An electromagnet uses a flow of electric current to generate a magnetic field. This magnetic field can interact with the magnetic field of a permanent magnet, causing a repulsive force between the two. The strength of the repulsive force depends on the strength of the electromagnet's magnetic field and the distance between the two magnets.

## 2. Can any electromagnet repel a permanent magnet?

In order for an electromagnet to repel a permanent magnet, it must have a stronger magnetic field than the permanent magnet. This means that the electromagnet must have a strong enough flow of electric current and be placed at the appropriate distance from the permanent magnet. Additionally, the polarity of the electromagnet's magnetic field must be opposite to that of the permanent magnet.

## 3. What factors affect the strength of an electromagnet's repulsive force?

The strength of the electromagnet's magnetic field and the distance between the two magnets are the main factors that affect the strength of the repulsive force. Other factors that can impact the strength include the type of material used to create the electromagnet, the shape and size of the electromagnet, and any external magnetic fields that may be present.

## 4. Can an electromagnet be used to completely repel a permanent magnet?

No, an electromagnet can only generate a repulsive force strong enough to counteract the attractive force of a permanent magnet. This means that the two magnets will never fully repel each other, but the repulsive force can make it seem as though the permanent magnet is being repelled.

## 5. Are there any practical applications for repelling a permanent magnet with an electromagnet?

Yes, there are several practical applications for this phenomenon. For example, it can be used in magnetic levitation trains to repel the train from the tracks, reducing friction and allowing for faster speeds. It can also be used in magnetic bearings to create a frictionless rotation in machinery. Additionally, it is commonly used in various types of research and experiments involving magnets and magnetic fields.

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