Bar magnet wrapped in electromagnetic coil

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Discussion Overview

The discussion revolves around the interaction between a bar magnet and an electromagnetic coil wrapped around it, specifically exploring whether applying current to the coil can amplify the magnetic field of the bar magnet while maintaining its shape. The scope includes theoretical considerations and practical implications related to magnetism and electromagnetism.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant proposes that wrapping a coil around a bar magnet and applying current could amplify the magnetic field of the bar magnet.
  • Another participant counters that a permanent magnet has a saturated magnetization, and applying an additional field will only add to the existing field without amplification.
  • A subsequent participant questions the distinction between "stronger" and "bigger" in the context of the magnetic field, seeking clarification on the nature of the field's strength.
  • Further clarification is provided that the magnetic field is indeed stronger as it results from the sum of the permanent magnetization and the applied solenoidal field, but the concept of "amplification" in this context is challenged.
  • Another participant inquires about the practical feasibility of doubling the strength of a specific neo bar magnet using this method, considering factors like heat generation and current supply limitations.
  • A response emphasizes that the forum is not a design engineering service and suggests the inquirer refer to the hysteresis curve and relevant formulas to address their question independently.

Areas of Agreement / Disagreement

Participants express differing views on the interaction between the magnetic fields, with some arguing against the possibility of amplification while others explore practical applications and limitations. The discussion remains unresolved regarding the feasibility of doubling the magnetic strength without overheating.

Contextual Notes

Participants mention the hysteresis curve and the relationship between the number of turns in the coil, current, and heat dissipation, indicating that these factors are crucial in determining the outcome but remain unresolved in the discussion.

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If I wrap a coil around a bar magnet and shoot current through the coil so that the magnetic field of the electromagnet is at the same polarity of the bar magnet will I have amplified the magnetic field of the bar magnet maintaining the same magnetic shape but bigger/stronger?
 
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No. A permanent magnet has a saturated magnetization (it is called "remanent magnetization" on the material's hysteresis curve). Applying additional field will simply add the field of the coil to the field of the magnet.
 
Does that mean the field will be stronger but not bigger?
 
"Stronger" vs. "bigger" doesn't make sense. The field is stronger--it's the sum of the permanent magnetization and the applied solenoidal field. There is no "amplification," used in the sense that a ferromagnetic material produces a strong B field in the presence of a weak H field.
 
Could I practically double the strength of a 4''x 0.5'' 35lb strength neo bar magnet using this method without overheating? Current supply isn't a problem for me, assume I have unlimited power for now, but I need to keep the added dimensions to a minimum so I don't know if i can pack that much magnetic strength into that small of an area or not.
If I increase the windings the magnetic field and wire resistance goes up and so does the heat generation limiting the current, if I decrease the windings the current goes up and the magnetic field is proportionally smaller requiring gobs of current. In either scenario I'm not sure whether I can achieve a "doubling" of magnetic strength without cooling methods. What do you think?
 
Physics Forums isn't a "we'll perform your design engineering for you for free" service. Look at the hysteresis curve and the formula for field from a solenoid. Figure out number of turns, current and heat dissipation and see if you can answer your question.
 

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