I don't understand how magnetic field work.Lets assume there is a random iron filing near a bar magnet,and it is present near the middle of the bar magnet,where the north and south pole of the magnet meet,it is not on the magnet,but near the area where the 2 poles of magnet meet,IT IS PRESENT NEAR THE NON POLAR REGION(REGION OF THE BAR MAGNET INSTEAD OF POLE),When an iron filling is present,magnet applies a force on it,then it spins and aligns itself in the direction in which it experiences force,which is a part of the magnetic field line passing through that point,but, if that force is enough to overcome friction,it will go and stick with the magnet,but,since maximum strength is at the poles,why doesn't it go and stick to the poles?why some iron filling stick in non polar region(places instead of pole of the magnet) of magnet?if it is due to friction,how did they overcome the friction to go and stick with the magnet in non polar region?a random iron filling has 2 choices,if magnetic force is enough to overcome friction,it has choice to go and stick in the poles of the magnet or in the non polar region,why doesn't it go to the pole?if u say the friction involved in going to the polar region is more than the friction involved in going to non polar region(Because it is closer to the non polar region),then it should try to go to the pole and stop in the middle of its way,why doesn't it even try to go the pole,can somebody explain it to me,I'm in 10th grade and I know only a few basic things,but these doubts still trouble me,if I'm wrong somewhere, please correct me


2 Answers 2


The picture


shows what happens to iron filings near a bar magnet. Notice how the filings tend to form into lines. These lines show where the magnetic field lines go. You will see some of the filings sticking to the side of the magnet; that is because the magnetic field comes out of the side of the magnet there. You can even see some curves coming from halfway between the centre and the ends. The magnetic field comes out of the sides of the bar magnet everywhere except exactly half-way along.

The reason the filings line up as they do is because each filing is quite long and thin, so each filing tends to line up with the magnetic field, giving it a N end and a S end. If you think about any one filing (say filing #1), the next filing along the field line will have its N end close to the S end of filing #1, so it will be attracted to it and they will tend to stick together. On the other hand a filing next to filing #1 will have its N end close to the N end of filing #1, and its S end near the S end of filing #1, and so it will be repelled from filing #1.

Friction needs to be overcome somehow to form patterns like this. Often this is done by sprinkling the filings, so the magnetic field can pull them into place as they fall. The magnetic force on each filing is along the lines they form, rather than sideways. Even when there only a few filings stuck to the magnet, you can notice how they stand up rather than lying flat. In this situation the filings might tend to move towards the ends of the magnet because the field is stronger there, but friction prevents it.

  • $\begingroup$ there are answers are here physics.stackexchange.com/questions/349464/… , and a picture $\endgroup$
    – anna v
    Feb 8 at 7:22
  • $\begingroup$ Duplicate Why don't the iron filing all goes to the North pole? $\endgroup$
    – Farcher
    Feb 8 at 8:23
  • $\begingroup$ Can u please answer this question?do different regions of a magnet have different strength?like the pole is stronger than non polar region,if that is so,then how is the total magnetic strength of the magnet determined? $\endgroup$ Feb 8 at 10:10
  • $\begingroup$ Visually the magnetic field lines are closer together where the field is stronger. The field lines are loops (and they never cross). They are (arbitrarily) taken to be coming out of the magnet at or near the North pole and going into the magnet at the South pole. At one time experiments were done using long magnets with a round ball at each end, to try to simulate a single pole. These days you are more likely to see experiments using electricity to generate a magnetic field. The field is strongest inside at the very centre, where all the lines are squashed together. $\endgroup$
    – Peter
    Feb 8 at 11:16
  • $\begingroup$ Thanks peter a lot $\endgroup$ Feb 9 at 10:15

If the iron filings experienced no friction, and no interference with other iron filings, then they would each tend to move to one or the other of the poles where the magnetic field is strongest.

However, the filings do experience friction, and it is only in areas where the magnetic force is sufficiently strong that the filings move away from their location, as opposed to just rotating.

In the picture, you will see an area which is almost devoid of filings, and that is the area where the field is strong enough to overcome the friction and cause filing translation.

Outside of that area, the filings mostly rotate (without translation), although there is an effect whereby the filings make a local disturbance in the magnetic field, and cause nearby filings to join up with them.

Between the depleted region and the magnet proper, filings are stuck to the magnet. Friction between the filings and the magnet's surface, as well as interference with other filings, prevents the filings from moving freely to the poles.

  • $\begingroup$ Thanks a lot sir/mam $\endgroup$ Feb 10 at 12:51

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