Jump to content
Sign in to follow this  
  • entries
  • comments
  • views

Physics of Magnetism

Sign in to follow this  


Mr. Fullerton recently gave us a hand out explaining electromagnetism and how it directly relates to Einstein's Theory of Special Relativity.  According to the theory, length and time are not absolute measures, but can be perceived differently based on the motion of the observer. This can be applied to current in a wire. Take a wire with no current flowing in it. As a whole, the wire is neutral as there are equal numbers of protons and electrons. When current flows through the wire, the electrons flow in a specific direction. The density of positive and negative charges in any section of the wire is the same, however, making the wire still neutral. Imagine a charged observer object moving outside the wire. The charges within the wire experience different motion relative to the charged object, so the separations of protons and electrons differ slightly from the observer's perspective, creating a difference in charge density, leading to a non zero net electrical charge, and therefore a net electric field. The charged observer sees the wire as having a net electric charge; therefore, it experience a magnetic force. It is crazy to think that the charged observer would experience a force simply because of what it perceives in the wire; even though the wire is neutral, it is not neutral to the charged observer. Crazy stuff. 

Sign in to follow this  


Recommended Comments

There are no comments to display.

Add a comment...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Terms of Use

The pages of APlusPhysics.com, Physics in Action podcasts, and other online media at this site are made available as a service to physics students, instructors, and others. Their use is encouraged and is free of charge. Teachers who wish to use materials either in a classroom demonstration format or as part of an interactive activity/lesson are granted permission (and encouraged) to do so. Linking to information on this site is allowed and encouraged, but content from APlusPhysics may not be made available elsewhere on the Internet without the author's written permission.

Copyright Notice

APlusPhysics.com, Silly Beagle Productions and Physics In Action materials are copyright protected and the author restricts their use to online usage through a live internet connection. Any downloading of files to other storage devices (hard drives, web servers, school servers, CDs, etc.) with the exception of Physics In Action podcast episodes is prohibited. The use of images, text and animations in other projects (including non-profit endeavors) is also prohibited. Requests for permission to use such material on other projects may be submitted in writing to info@aplusphysics.com. Licensing of the content of APlusPhysics.com for other uses may be considered in the future.

  • Create New...