Piece of metal being carried through an inductor

In summary, the conversation discusses the behavior of a piece of metal traveling through an inductor with DC current flowing through it, specifically in the context of a solenoid with a hole in the middle. The questions revolve around the time it takes for the inductor to reach its peak magnetic field output, the potential disruption of the current/magnetic field by the metal, and the behavior of the metal in the solenoid. The conversation also touches on the use of free electrons and the Lorentz force to understand and model the behavior. Additionally, the differences in behavior between non-magnetic metals and iron are mentioned.
  • #1
guss
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Hi, I have some questions about a piece of metal traveling through an inductor with DC current flowing through it. Imagine a solenoid of sorts with a hole in the middle that a piece of neutrally charged metal travels through, sort of like a coil gun.

Let's say the inductor has no current running through it, then we turn it on. It will take time to get up near it's peak magnetic field output, correct? I know the current takes time to get going, and the magnetic field is proportional to the current. And if the piece of metal is attracted to the solenoid, then the piece of metal will travel through the solenoid. Will the piece of metal being attracted by and traveling through the solenoid disrupt the current/magnetic field of the solenoid? As in, will the solenoid take longer to "get going" if it is attracting a piece of neutral metal?

My last question is, will the piece of metal be attracted to both sides of the solenoid (instead of attracted by one and repelled by the other) even though the magnetic field goes straight through the solenoid? I'm pretty sure the answer is yes but I'm just making sure.

Thanks!
 
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  • #2
I would model this using the free electrons moving into the B field of the solenoid.
What direction are the free electrons moving in the B field. And then use the Lorentz force to see which way the electrons will move in the conductor. Will there be an induced current in the conductor and if so what direction is it? F=q(vxB)
Good questions you bring up.
 
  • #3
Thanks, but I still have a lot of difficulties. Such as, the force acting on the electrons is in the same direction as the magnetic field in the solenoid.
 
  • #4
guss said:
Hi, I have some questions about a piece of metal traveling through an inductor with DC current flowing through it. Imagine a solenoid of sorts with a hole in the middle that a piece of neutrally charged metal travels through, sort of like a coil gun.
Copper and aluminium (non-magnetic) will behave differently to steel and nickel.
My last question is, will the piece of metal be attracted to both sides of the solenoid (instead of attracted by one and repelled by the other) even though the magnetic field goes straight through the solenoid? I'm pretty sure the answer is yes but I'm just making sure.
If you quickly slide the iron core into an energized solenoid, the core can travel through and partly emerge from the far end, then get pulled back in, then bounce back and forth until it settles.

Iron dropped into the solenoid just as it's being energized will increase the inductance, causing the coil's current to rise more slowly. :smile:
 
  • #5


I can provide some insights into your questions about a piece of metal traveling through an inductor with DC current flowing through it.

Firstly, you are correct in assuming that it will take time for the inductor to reach its peak magnetic field output when the current is turned on. This is because the magnetic field is directly proportional to the current, so it will take time for the current to build up and for the magnetic field to reach its maximum strength.

Regarding your second question, the piece of metal being attracted to and traveling through the solenoid will not disrupt the current or magnetic field of the solenoid. This is because the metal is neutrally charged, meaning it has no net charge and therefore does not interact with the magnetic field. The current in the solenoid will continue to flow and the magnetic field will remain unaffected.

As for your last question, the piece of metal will be attracted to both sides of the solenoid. This is because the magnetic field created by the solenoid is a uniform field that goes straight through the solenoid. The metal will therefore experience a force in the same direction on both sides of the solenoid, causing it to be attracted to both sides.

I hope this helps to answer your questions and provide a better understanding of the behavior of a piece of metal traveling through an inductor with DC current.
 

1. How does a piece of metal being carried through an inductor create an electric current?

When a piece of metal is moved through an inductor, it cuts through the lines of magnetic flux created by the inductor. This movement induces an electric current in the metal, according to Faraday's law of induction.

2. Does the size or shape of the metal piece affect the induced current?

Yes, the size and shape of the metal piece can affect the induced current. A larger or longer piece of metal will cut through more magnetic flux and therefore induce a larger current. The shape of the metal can also affect the direction and strength of the induced current.

3. Does the speed of the metal piece affect the induced current?

Yes, the speed of the metal piece can affect the induced current. A faster-moving metal piece will cut through more magnetic flux per unit time, resulting in a larger induced current. Conversely, a slower-moving metal piece will induce a smaller current.

4. How does the inductance of the inductor affect the induced current?

The inductance of the inductor is a measure of its ability to induce a current in a nearby conductor. A higher inductance will result in a larger induced current, while a lower inductance will result in a smaller induced current.

5. Are there any safety concerns when working with a piece of metal being carried through an inductor?

Yes, there can be safety concerns when working with a piece of metal being carried through an inductor. The induced current can be strong enough to cause electrical shocks or burns, so it is important to take proper precautions and use appropriate safety equipment when working with inductors.

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