# Moving an iron sphere along a path with an electromagnet

• edmundsj
In summary, the conversation involves someone seeking information about the possibility of using an electromagnet to move iron nanoparticles through a non-magnetic gel using a magnetic field gradient. The person has limited knowledge in physics and is looking for guidance on how to create such a device. It is mentioned that a magnetic field gradient of 50T/m is needed and that it is possible to achieve this, but not trivial over a distance of 5cm. There is also a discussion about the challenges of creating such a device and the possibility of purchasing high gradient magnets for this application. The depth at which the nanoparticles need to be moved and any potential contraindications for high magnetic fields are also mentioned.
edmundsj
Hello,

So I am working on a project that requires the movement of iron nanoparticles (let's assume 25nm in diameter, and let's assume the sphere is uniform and pure iron) through a (non-magnetic) gel using an externally applied magnetic field. Let's assume the total distance I want to move the particle is 5cm. The force I need to exert on each nanoparticle individually to move them through the gel is at most 20pN. I have no physics background, but what I think I know is that to move a magnetic particle along a straight path with constant force I will need to apply a magnetic field gradient that is roughly equivalent at each point along the path. I believe this magnetic field gradient should be on the order of 50T/m.

Is it possible to achieve this using an electromagnet? Is there a name for this type of device that I can look up? How might I go about creating such a device if it is possible? I'm just looking for someone to point me in the right direction. Please assume if you post a formula that I'm a 10-year old with only a basic understanding of electromagnetism.

50 T/m is possible, but getting this over 5 cm is not trivial. As an example, state-of-the-art LHC magnets have ~250 T/m over a few centimeters.
There are a few applications (e.g. MRI), so it might be possible to buy those magnets. Creating one yourself... I don't know. The LHC magnets are superconducting, with normal-conducting magnets it will be challenging to get high gradients and you certainly don't have the tools to make very good coils.

edmundsj said:
Please assume if you post a formula that I'm a 10-year old with only a basic understanding of electromagnetism.

You sell yourself short!

Can you say more about the application? At what depth in the "gel" will you need to move the nanoparticles? Are there any contraindications for high magnetic fields in this application?

## 1. How does an electromagnet work?

An electromagnet works by using electricity to create a magnetic field. When an electric current flows through a wire, it generates a magnetic field around the wire. By wrapping the wire into a coil and passing a current through it, the magnetic field is amplified, creating a stronger force that can attract or repel objects.

## 2. How can an electromagnet move an iron sphere along a path?

An electromagnet can move an iron sphere along a path by creating a magnetic field that attracts the sphere. By turning the electromagnet on and off or changing the direction of the current, the magnetic force can be controlled to move the sphere along a designated path.

## 3. What factors affect the strength of an electromagnet?

The strength of an electromagnet depends on the number of turns in the coil, the amount of electric current passing through the coil, and the material of the core. Increasing the number of turns and the amount of current will increase the strength of the magnetic field, and using a ferromagnetic material for the core will also increase the strength of the electromagnet.

## 4. Can an electromagnet be turned on and off?

Yes, an electromagnet can be turned on and off by controlling the flow of electric current. When the current is turned off, the magnetic field dissipates, and the electromagnet loses its magnetic force. This property makes electromagnets useful for various applications, such as lifting and moving objects.

## 5. What are some real-life applications of moving an iron sphere along a path with an electromagnet?

Some real-life applications of moving an iron sphere along a path with an electromagnet include conveyor belts in manufacturing plants or warehouses, magnetic levitation trains, and magnetic resonance imaging (MRI) machines in the medical field. Electromagnets are also commonly used in cranes and motors for lifting and moving heavy objects.

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