Electromagnets and Permanent Magnets: Equal Repulsion Force?

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Discussion Overview

The discussion revolves around a homework problem concerning the forces exerted by an electromagnet and permanent magnets. Participants explore how the repelling force of an electromagnet, fixed to the floor, interacts with two permanent magnets placed at a distance. The focus is on understanding the distribution of force and the expectations of a science class assignment.

Discussion Character

  • Homework-related
  • Exploratory
  • Debate/contested

Main Points Raised

  • John poses a question about whether the repelling force of one kilogram from the electromagnet is equally applied to each permanent magnet or divided between them.
  • Some participants suggest that if there is only one permanent magnet, its gauge would show 1 kg, but the implications for two magnets remain unclear.
  • There is a discussion about the understanding of forces, with some participants questioning whether the granddaughter has learned about concepts like tension and compression.
  • John expresses uncertainty about the teacher's expectations and suggests that the assignment may be more about intuition than technical accuracy.
  • One participant mentions that the forum is not designed to solve problems directly but to help users find their own solutions.

Areas of Agreement / Disagreement

Participants do not reach a consensus on how the forces are distributed between the magnets. There are varying interpretations of the problem and the educational intent behind the assignment, leading to multiple competing views.

Contextual Notes

Participants note that the granddaughter's understanding of physics is still developing, and the discussion reflects a range of assumptions about her prior knowledge and the nature of the homework problem.

Who May Find This Useful

This discussion may be of interest to educators, parents assisting children with science homework, and individuals curious about basic principles of electromagnetism and force distribution.

johntee
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Homework Statement



My 10 year old granddaughter started her new school term last week and was presented with an electromagnet problem by her new science teacher. The class is allowed to use any non-physical method to solve this for their lesson next Wednesday. A direct link to my 'Dropbox' account show the picture she was given at school.

She needs to know:- Will the example electro-magnets repelling force of one kilogram be applied equally to each of the permanent magnets, or will the repelling force be divided by two, equating to the one kilogram electro-magnet force exerting 0.5 kilogram against each of the permanent magnets?

Homework Equations



https://www.dropbox.com/s/srdn5w8krhlpgth/Electro-magnet%20-%20Copy.jpg

The Attempt at a Solution



Only me of course; Granddad can sort anything out :!) Oh the faith of children.

Thanks in advance,

John

Homework Statement


Homework Equations


The Attempt at a Solution


Homework Statement


Homework Equations


The Attempt at a Solution


Homework Statement


Homework Equations


The Attempt at a Solution

 
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hello johntee! welcome to pf! :smile:

ask your granddaughter what she would expect to happen if the electromagnet were glued to the floor :wink:
 
Hi tiny-tim,

Thanks for your welcome. Apparently the electromagnetic is glued to the floor and the permanent magnets can only move outwards in the directions as shown by the arrows, I did not realize that when posting her question. She recognizes the permanent magnets could spin around and stick to the electromagnet, but that is not what her teacher requires, he wishes the class to evaluate the repelling push pressure if an individual pressure gauge was placed on each outside end of the fixed magnets. Will the gauges each show one kilogram or would they show 0.5 kilograms. I hope this makes sense to you, I 'fluffed' at physics during my school days in the 1950's so I don't have a clue how to explain things better.

Thanks,

John

PS. My daughter will be carting my granddaughter off to her bath and thereafter bed shortly in readiness for school at 6:30 am in the morning. I dare not ring after about 7:00pm. My daughter is a school teacher so double school runs start early.
 
Last edited:
hi john! :smile:
johntee said:
… the electromagnetic is glued to the floor and the permanent magnets can only move outwards in the directions as shown by the arrows … Will the gauges each show one kilogram or would they show 0.5 kilograms.

ah, so if there was only one permanent magnet, its gauge would show 1 kg

does your granddaughter know anything about forces? or tension or compression?

would it make any sense to ask your granddaughter what force the glue exerts on the electromagnet?
 
Hello again tiny-tim,

Just got off the phone to her, my daughter had to break her away from her iPad. I explained that if there was one magnet in place the permanent magnet gauge would show 1 Kg, whereupon she asked what about the other gauge on the other magnet. Of course I could not answer. The class only started science lessons last September and are only on fundamentals, i.e. Basic circuits using LED's and batteries to demonstrate such. They were intruded to permanent magnets before Christmas. She doesn't know anything about the forces / tensions / compressions, I assume they would come later in her science schooling. All the class was told was the electromagnet is fixed to the floor and the permanent magnets were being repelled, no mention of glues etc. I personally believe their teacher is looking for a basic result of the supplied photograph, a test of their intuition maybe rather than a result inclusive of any untaught laws at the moment?

Once again, I cannot assist her further hence my posting here.

Thanks,

John

PS. My daughter will be carting my granddaughter off to her bath and thereafter bed shortly in readiness for school at 6:30 am in the morning. I dare not ring after about 7:00pm. My daughter is a school teacher so double school runs start early.
 
Last edited:
hi john! :smile:
johntee said:
… All the class was told was the electromagnet is fixed to the floor and the permanent magnets were being repelled, no mention of glues etc. I personally believe their teacher is looking for a basic result of the supplied photograph, a test of their intuition maybe rather than a result inclusive of any untaught laws at the moment?

i don't think we can give her any more help

from here, she'll have to apply her female intuition! :smile:
PS. My daughter will be carting my granddaughter off to her bath and thereafter bed shortly in readiness for school at 6:30 am in the morning. I dare not ring after about 7:00pm. My daughter is a school teacher so double school runs start early.

erm :redface: …

i'd need to know your time-zone! :wink:​
 
Electro magnetic repulsion

tiny-tim said:
hi john! :smile:


i don't think we can give her any more help

from here, she'll have to apply her female intuition! :smile:


erm :redface: …

i'd need to know your time-zone! :wink:​

Hi tiny-tim,

I thought a forum like this would be the most promising avenue to solving my granddaughter's school problem in a very basic way, unfortunately not, unless any other members can assist us.

I have contacted an old school chum who made his living in the electronics field and he is going to get one of his staff to make a physical demonstration model of the fixed electromagnet and permanent magnets in the picture configuration as sent home from school. Whilst my granddaughter is forbidden to use such to solve her homework, she intends to take it into her school science class next Wednesday for her teachers evaluation. Maybe it will become a science class feature for other young pupils to use in the future.

In fairness, I don't think a child of ten years has developed the ability to apply 'female' intuition' to such a scientific challenge yet, with four months into the art being hardly suffice. So to the rescue comes 'good old, and wise granddad' once again. Children so obviously need our help in their early development years and it's to we, the adults, who need to rally to their assistance in any way we can.

Our time zone is that of the United Kingdom at present.

John
 
johntee said:
I thought a forum like this would be the most promising avenue to solving my granddaughter's school problem in a very basic way …

ah, this forum does not solve people's problems,

it only helps them to solve them themselves :smile:
 
tiny-tim said:
ah, this forum does not solve people's problems,

it only helps them to solve them themselves :smile:


Hi tiny-tim,

I would have welcomed that information after my first post when I requested such. It could have saved me valuable time pursuing a negative.

John
 
  • #10
johntee said:
I would have welcomed that information after my first post …

I assumed that you had read the forum's Rules and Guidelines. :redface:
 
  • #11
Hi tiny-tim,

Obviously not, a throw back from me being a professional architect ( now retired ). I delegated others to do that on my behalf whilst I got on with my main role in structural engineering and desgn.

John
 

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