Piece of metal being carried through an inductor

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Discussion Overview

The discussion revolves around the behavior of a piece of metal traveling through an inductor with direct current (DC) flowing through it. Participants explore the effects of the metal's motion on the magnetic field and current within the inductor, as well as the differences in behavior between various types of metals.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions whether the attraction of the piece of neutral metal to the solenoid will disrupt the current or magnetic field, and if this will affect the time it takes for the solenoid to reach its peak magnetic field output.
  • Another participant suggests modeling the situation using the movement of free electrons in the magnetic field and applying the Lorentz force to determine the direction of induced current in the conductor.
  • A participant expresses confusion about the direction of the force acting on the electrons, noting that it aligns with the magnetic field in the solenoid.
  • It is noted that different materials, such as copper and aluminum versus steel and nickel, will behave differently in the magnetic field.
  • One participant describes the behavior of an iron core when quickly slid into an energized solenoid, suggesting it can oscillate back and forth until it settles.
  • Another participant mentions that dropping iron into the solenoid as it is being energized will increase the inductance, causing the coil's current to rise more slowly.

Areas of Agreement / Disagreement

Participants express various viewpoints and uncertainties regarding the effects of the metal's motion on the solenoid's magnetic field and current. There is no consensus on the implications of these interactions or the behavior of different metals.

Contextual Notes

Participants discuss the influence of the type of metal on the behavior within the magnetic field, but the discussion does not resolve the specific conditions under which these effects occur. The assumptions regarding the nature of the magnetic field and the properties of the metals involved remain unclarified.

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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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.
 
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.
 
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:
 

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