why drill pipe always get magnetised after getting out from downhole?
441253
It has to do with the alignment of charge due to unidirectional striking force- The same thing will happen to any iron bar after a hard strike-the force generated causes (usually temporary) alignment of enough atoms to generate magnetism. In a normal bar of iron, the atoms are aligned more or less at random, so there is no cumulative directional magnetic force- Any time a significantly large proportion of atoms are aligned together, the summation of the electromagnetic charges can be detected.  Rotating a piece of metal will not induce magnetic charge.  Exposing iron to an extremely powerful magnetic field will, because it will cause alignment of the atoms in the iron, but the magnetic field of the Earth (inside, outside, everywhere) is extremely weak.
977140
DC Current flows through a long wire around ferrous core ,this establishes a magnetic field but is only half the function. If u substitute AC current it will magnetize and the field will fluctuate. Now if u rap some more wire around the AC exp. u will find that there will be current transformed across to the secondary winding with an turns ratio between the 2 coils with no physical connection.
1070520
Try this. Iron when combined with other metal elements becomes non-magnetic, yet with varying of the same elements is quite attracted to the magnet.Name the divisions of the metals and explain why.
944389
I researched this as a geology student 20 years ago and has interested me since then.  By researching cores of basalt, they have a pretty good idea what the magnetic field does when it starts to shift but it is somewhat random and slow.  I remember that typically, before the switch in polarization, the poles starts to migrate in a spiral as it is doing now.  It has been an extra long time since the last switch so it is due.  I suspect that it is about to switch (within the next thousand years or so) but no one can say for certain in my opinion.  Apparently there is a period of time (100 years or so) when the field is next to zero in strength.  I saw a show on it recently that demonstrated they have learned a lot since I studied it in school.
42980
it's called cathodic protection. the magnesium is sacrificed so the iron or steel pipe will last longer.
1167649
Not quite! The direction the water goes down the plug-hole depends on whther you are in the northern or southern hemisphere. It has nothing to do with magnetic fields, but everything to do with the coreolis effect, which is caused by the direction in which the Earth is spinning.
127751
By behaviour of magnetic field associated with any electric conductor, the field is at right angle to the direction of flow of current. Means if current flows along X Axis, magnetic field's plane lies in YZ plane.\n\nVice a versa, if changing magnetic field is in YZ plane and a conductor is placed in the area of influence of field, current is induced in the conductor which flows in the direction of X axis. Well, these are basics.\n\nIn any magnetic device like transformer, motor or choke this principle is used. To strengthen the magnetic field, magnetic materials such as Iron cobalt etc are used. Electric conductors are arranged in these devices in such a way that magnetic field produced by electric current is at picked up by the magnetic material which are called as "Core". When magnetic field produced by electric current, magnetizes this core and the current causing the field is "Oscillating" the magnetic field associated with current also oscillates. The core material whether it be Iron or Cobalt, is a metal. It may not be as good a conductor of electricity as copper or silver or gold, but it is a conductor and not insulator. This oscillating field within the core produces induced current within the core itself.\n\nSince any electric current flow finds the shorted least resistance path, this induced current circuit closes in a small loop and in this process many small loops of current are formed in the core. This is similar to circulating air in a whirlpool or eddys prodcued in the water when you drop a stone in the water. Hence these current loops are called Eddy Current.\n\nThese small loops of current, circulating in small circles cause heat to be developed which heats up the core. Since there is also a magnetic field associated with these current loops, and is in opposite directiont of the main field, it results in reduced magnetic field density etc etc.\n\nHowever, in induction heating furances this unwanted phenomenon is put to use.\n\nIs my answer just that what you are looking for?
1182896
Voltage applied to the primary coil of a transfer causes an electrical current to begin to flow, and that causes a magnetic field to form.  As the voltage drops back to zero and reverses, the field collapses and then forms in the opposite direction.  This changing magnetic field induces a voltage in the secondary coil.  If that coil is connected to some load, the voltage causes current to flow.\n\nIf the ferromagnetic core which concentrates and contains the magnetic field is laminated, and there is some room for these laminations to move, they move in response to the changing magnetic field.  If there is no movable magnetic material in the field, you hear nothing.\n\nIt need not be harmonic.  It depends only on how the magnetic material is affected by the force applied to it by the magnetic field, and that field depends on the variation of the applied voltage with time.  It need not be the sinusoidal pattern at 50/60 Hz of commercial power mains.  In a switching power supply, it's a square wave.
669781
Magnetic property of a material is due to the arrangement of Domains in it. If you are not of science background, simply think it as it is the arrangement of atoms of the material, which is responsible for its magnetism. If you provide a permanent magnet with electric supply, the arrangement of atoms in it will be disturbed resulting in loss or decrease in its magnetism.\nNot only the electric supply, but heating or even strong jerks can also lead to the disturbed atomic arrangement and therefore decreased or completely lost magnetism.
1064334
Drilling Rig , Via Wikipedia\n\nReverse circulation the course of drilling fluid downward through the annulus and upward through the drill stem. Also referred to as “circulating the short way,” since returns from bottom can be obtained more quickly than in normal circulation. Compare normal circulation.
507426
A common way is to stick a large drill bit on the end of drill pipes that are threaded together as need.  This is run down the center of a larger pipe called casing.
655524
http://en.wikipedia.org/wiki/Magnetic_Flux_Leakage\nThis is real good
883128
Use a magnet. Iron is attracted to it, lead is not.
975911
First of all, I'm not professional of physical. I don't know at all, but Iron and steel are really high permeability, and strongly attract to magnet. Seem like the steel bar would tell you which one rely force electron. I don't think Iron has any thing to do with steel.
294279
Decreasing the temp at which you are doing the bending will also help YS, although it's a tricky thing to find the lowest temp that you can still bend effectivley at.  Also, if you are annealing the pipe after bending then a drop in YS is a normal result.  To maintain a finer grain structure, and along with it the YS, make sure the pipe is held at a high temp for as short of a time as possible to avoid recovery.
1111173
Any magnet will stay magnetic forever unless it gets heated up or something.
177391
No\n\nThe reason this has\nnever happened is due to the source of magnetic fields:  moving electric\ncharges.  When electric charges (e.g. electrons) move in circles, they\nproduce a magnetic field.  In a piece of iron, it is very easy to line up\nthese circles, getting all the little magnets to work together as one big\nmagnet.\n\nFor each of these circles, one side is the north pole and one side is the\nsouth pole.  Since each circle has two sides, each circle has a north and a\nsouth pole.  Even the smallest possible magnets (spinning electrons) have a\nnorth and a south pole.