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## Physics library

### Course: Physics library>Unit 18

Lesson 2: Discovery of magnetic fields

# Magnetic permeability

What happens to the magnetic field of a magnet in the presence of a another material which is attracted to it. Why does this happen? Created by Brit Cruise.

## Want to join the conversation?

• How did you get the iron filings off of the magnet?
• get a stronger electromagnet so the fillings stick to there, then demagnetize the electromagnet :)
• How come the iron bar did not collect any iron fillings?? Did the red magnet "hog" all of the magnetism, or was it because the iron bar was already attracted to the red magnet??
• because the metal was attached to both the poles so the metal was probably neutralized as we seen in the previous videos.
• If iron filings clump up on the steel plate when it is on the magnet, how does the steel plate react to the iron filings?
• As the video says "to the material or block which is in contact to the magnet, iron fillings are not attracted.......in the same way when 1 iron filling is in contact with magnet it should not attract the other 1....but they are forming a chain !! how is it possible..
• Will anyone tell me what basically is the meaning of this presentation?
• Notice that when the bar is attached to the magnet the distance over which the force interacts with the iron filings decreases. It seems as though the steel bar is acting as a magnetic shield....
(1 vote)
• In this video does anyone know what material was used to "block" the magnetism?
• It almost looks as if when he puts the magnet down, the iron filings are repelled and they create a space around it...but that seems wrong. They didn't just all attract to the magnet, right? It didn't look like there were that much filings on the magnet...
(1 vote)
• The field weakens, the further away from the magnet you are. So yes, the filings closer in were attracted, whereas the ones further out were not. Sort of like the event horizon on a black hole, there is a point at which you cannot escape.