Weak & Strong Magnet attract each other no matter what polarity

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Discussion Overview

The discussion centers on the behavior of weak and strong magnets in terms of attraction and repulsion, particularly in the context of electromagnets and permanent magnets. Participants explore the underlying mechanisms and conditions that influence these interactions, including the effects of magnet polarity and material properties.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants observe that a strong magnet attracts a weak permanent magnet or electromagnet regardless of polarity.
  • One participant notes that increasing the power to the electromagnet can lead to repulsion, indicating a change in behavior based on strength.
  • Another participant suggests that the weak magnet behaves like an ordinary piece of iron when influenced by a strong magnet.
  • There is a hypothesis that the stronger magnet's field may temporarily realign the domains of the weaker magnet, potentially reversing its polarity under certain conditions.
  • A participant expresses interest in understanding the relative strengths of magnets needed for both attraction and repulsion and seeks resources on the topic.
  • One reply mentions the distinction between "magnetically hard" and "magnetically soft" magnets as relevant to the discussion.

Areas of Agreement / Disagreement

Participants express various hypotheses and observations, but there is no consensus on the mechanisms or conditions under which attraction and repulsion occur. Multiple competing views remain regarding the behavior of the magnets.

Contextual Notes

Participants reference the need for further information on the strength of magnets and methods to measure field strength, indicating potential limitations in their current understanding and experimental setup.

Who May Find This Useful

This discussion may be of interest to those studying magnetism, electromagnetism, or related experimental physics, as well as individuals involved in practical applications of magnets in projects.

sachooo
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Recently while working with electromagnet , we noticed one thing.

I we bring strong magnet near very weak PM or electromagnet, It will attract the weak one whatever is the polarity of magnets.

we increased power to electromagnet then it was giving repulsion.

I did't understand this phenomenon can anybody explain this to me.
 
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sachooo said:
Recently while working with electromagnet , we noticed one thing.

I we bring strong magnet near very weak PM or electromagnet, It will attract the weak one whatever is the polarity of magnets.

we increased power to electromagnet then it was giving repulsion.

I did't understand this phenomenon can anybody explain this to me.

Welcome to the PF.

What are electromagnets constructed of? You wind wire around what kind of metal?
 
berkeman said:
Welcome to the PF.

What are electromagnets constructed of? You wind wire around what kind of metal?

We used simple mild steel but we observed this behaviour with permanant magnets too.
 
A strong magnet will attract an ordinary piece of iron. In the case where the weak magnet is very weak, it behaves more like an ordinary piece of iron than a strong magnet.
 
To express this in more detail I think(but do not know enough about domain theory to be sure)that the field of the stronger magnet temporarily realigns the domains of the weaker magnet such that attraction always occurs.As an example if the N pole of the stronger magnet were brought close to the N pole of the weaker magnet then the domains of the weaker magnet would be flipped round such that its poles reverse.Perhaps if contact was maintained for a long enough time the polarity reversal of the weaker magnet would become permanent.What happens must also depend upon the types of magnets used as well as their strengths.
 
Dadface said:
To express this in more detail I think(but do not know enough about domain theory to be sure)that the field of the stronger magnet temporarily realigns the domains of the weaker magnet such that attraction always occurs.As an example if the N pole of the stronger magnet were brought close to the N pole of the weaker magnet then the domains of the weaker magnet would be flipped round such that its poles reverse.Perhaps if contact was maintained for a long enough time the polarity reversal of the weaker magnet would become permanent.What happens must also depend upon the types of magnets used as well as their strengths.


Thanks You all for this information.

In our project We are trying to attract & repel permanant magnet. To get max force we tried use high power permanant magnet & so we had this problem.
But now I would like know what should be relative strength of both magnets sothat there will be attraction & repulsion both.

Is there any document or book dealing this issue.

Is there any method to measure field strength with multimeter CRO. ( normal electronics Lab instruments )
 
Hello sachooo.It is relevant to know the difference between "magnetically hard" and "magnetically soft" magnets.I think the Wiki article entitled "magnet" contains all of the information you need and more.
 

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