Canceling Magnetic & Electric Fields: An O Level Student's Guide

  • Thread starter Ahmed Abdullah
  • Start date
In summary, a magnetic shield and Faraday cage can protect against the field of a charge, and molecules that are electrically neutral can create an electric field.
  • #1
Ahmed Abdullah
203
3
Here is some very fundamental things troubling me. It follows...
How we can cancel
(1) the magnetic field produced by a magnet(so that there will be no magnetic field)
(2)the electric field produced by a charge (so that there will be no electric field)

Does same numbers of positive and negative charges cancel the field of each other in such a way that we have no electric field at all? Sounds silly but atoms are electrically neutral that way. If it is not that way then what is the definition of electrically neutrality? Is it not about having no net electric field?
In the same way, how two electrons in the same orbital having opposite spin cancel out the magnetic field of each other?

please explain in simple and basic terms (m An O level student) .
 
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  • #2
Ahmed Abdullah said:
Here is some very fundamental things troubling me. It follows...
How we can cancel
(1) the magnetic field produced by a magnet(so that there will be no magnetic field)
(2)the electric field produced by a charge (so that there will be no electric field)

Does same numbers of positive and negative charges cancel the field of each other in such a way that we have no electric field at all? Sounds silly but atoms are electrically neutral that way. If it is not that way then what is the definition of electrically neutrality? Is it not about having no net electric field?
In the same way, how two electrons in the same orbital having opposite spin cancel out the magnetic field of each other?

please explain in simple and basic terms (m An O level student) .

(1) You can enclose the magnet in a magnetic shield. That is, a closed "box" formed by a high magnetic permeability alloy (as mu-metal) thick enough. How much thick depends on the magnetic flux that the shield has to "short-circuit".

(2) You can enclose the charge in a Faraday cage. That is, a closed conductive box. Any thickness work.

Positive and negative charges do not cancel unless they have the same total value and they have the good distribution in space. One "good" distribution is all positive or negative charge in the center surrounded uniformly by the charge of opposite sign (as an atom).

Some molecules (as water) are electrically neutral as they have as many electrons as protons. But the charges are not distributed in the "good" way, and they produce an electric field.

Full orbitals have each level filled with electrons of opposite spin, which cancel each other. These orbitals do not contribute to the magnetic field of the atom.
 
  • #3
How does a magnetic shield work (in the simillar way a faraday cage does, I hope!)?
 
  • #4
No. A magnetic shield is something that "conducts" the magnetic field much better than air, vacuum, etc. Lines of field "prefer" to pass through this material instead of traversing it, make a tour in the other side, and traverse the shield once again. But if you put a sheet of shield between the two poles of a horseshoe magnet, the field lines will happily traverse the shield to go from one pole to the other.
P.S. Do not tell anyone that I used the terms "conduct" and "prefer". It is not very scientific https://www.physicsforums.com/images/icons/icon12.gif
Wink
 
Last edited by a moderator:
  • #5
Thx a lot. :)
 

1. What is the purpose of "Canceling Magnetic & Electric Fields: An O Level Student's Guide"?

The purpose of this guide is to provide O Level students with a comprehensive understanding of how to cancel magnetic and electric fields, which is a fundamental concept in physics. It aims to help students improve their conceptual understanding and problem-solving skills in this topic.

2. Who can benefit from this guide?

This guide is designed for O Level students who are studying physics and want to deepen their understanding of magnetic and electric fields. It can also be helpful for teachers who are looking for additional resources to supplement their lessons.

3. Can this guide be used for other levels or exams?

While the guide is specifically tailored for O Level students, the concepts and principles discussed are applicable to other levels and exams such as A Level and college entrance exams. However, the level of difficulty may vary, and students are advised to consult their respective syllabus for specific requirements.

4. What topics are covered in this guide?

This guide covers the basics of magnetic and electric fields, including their properties, interactions, and calculations. It also delves into the concept of canceling fields and provides step-by-step explanations and examples to help students master this topic.

5. Is this guide suitable for self-study?

Yes, this guide is suitable for self-study as it provides clear and concise explanations, along with practice questions and answers for students to check their understanding. However, it is recommended to seek help from a teacher or tutor if any difficulties are encountered.

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