Coils what would happen

Status
Not open for further replies.

Eddy Current

Senior Member
I know that you take a coil and run a magnet through it to induce a voltage but what would happen if the coil were magnetic also?
 

cadpoint

Senior Member
Location
Durham, NC
I know that you take a coil and run a magnet through it to induce a voltage but what would happen if the coil were magnetic also?

A new line of transforms (manufacture) came out oh about ten years ago that used higher magnetic material in both the wiring and the coor. Its a sudo simple ratio problem that less power required to obtain some desired result using this type of materals, will be just that.
 

Eddy Current

Senior Member
A new line of transforms (manufacture) came out oh about ten years ago that used higher magnetic material in both the wiring and the coor. Its a sudo simple ratio problem that less power required to obtain some desired result using this type of materals, will be just that.

What were the used in?
 

cadpoint

Senior Member
Location
Durham, NC
For transformers and the wiring that they used. The copper was at higher percentage overall and the core had a higher magnetic valve overall than.
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
I know that you take a coil and run a magnet through it to induce a voltage but what would happen if the coil were magnetic also?

The only way that "the coil" could "be magnetic also." would be if the coil were made of iron (or other magnetic) wire. And even then that would not have any particular direct effect on the induced voltage in the coil. There might be a greater change in the local magnetic field in the area of the coil as the magnet is moved through it, which could then induce a higher voltage and/or current.
If you have a static magnetic field which has been produced by magnetizing the iron wire, that by itself would have no effect at all on the induced voltage or current. And you would have to have the turns of the wire in close contact to allow a sizable magnetic field to be induced.

One way to test experimentally whether this is happening or not is to see whether there is a greater resistance to moving the magnet through the coil because of the induced magnetic field in the coil material itself.

It is an interesting physics question, which I cannot give a definitive answer to at the moment, but AFAIK it would not be used in any practical application.

In generators (alternators) which use permanent magnets, the copper wire coil is usually wound around a magnetic material core (pole piece). That is there to increase the change in magnetic field inside the coil as the magnets move by. But I would not call this a case of the coil being magnetic.

PS: This is one of those questions where I cannot tell without more interaction whether you are asking a meaningless question about a concept you do not understand or a really sophisticated one, so my answer may be somewhere in between too.
 
Last edited:

Ravenvalor

Senior Member
The only way that "the coil" could "be magnetic also." would be if the coil were made of iron (or other magnetic) wire. And even then that would not have any particular direct effect on the induced voltage in the coil. There might be a greater change in the local magnetic field in the area of the coil as the magnet is moved through it, which could then induce a higher voltage and/or current.
If you have a static magnetic field which has been produced by magnetizing the iron wire, that by itself would have no effect at all on the induced voltage or current. And you would have to have the turns of the wire in close contact to allow a sizable magnetic field to be induced.

One way to test experimentally whether this is happening or not is to see whether there is a greater resistance to moving the magnet through the coil because of the induced magnetic field in the coil material itself.

It is an interesting physics question, which I cannot give a definitive answer to at the moment, but AFAIK it would not be used in any practical application.

In generators (alternators) which use permanent magnets, the copper wire coil is usually wound around a magnetic material core (pole piece). That is there to increase the change in magnetic field inside the coil as the magnets move by. But I would not call this a case of the coil being magnetic.

PS: This is one of those questions where I cannot tell without more interaction whether you are asking a meaningless question about a concept you do not understand or a really sophisticated one, so my answer may be somewhere in between too.

Good explanation of electromagnetism.
 

Ravenvalor

Senior Member
Someone just recently explained to me how when electricity is running through a conductor a magnetic field is also present around the conductor. When you wrap that conductor up in a ball or a circle the magnetic fields are pressing up against each other which acts to slow down the flow of electricity through the conductor. If this conductor was feeding a light bulb there would be a delay before the light bulb comes on. Likewise when you disconnect the conductor from its power supply there is a delay before light bulb goes off.
I probably got that wrong but hopefully this paper's not being graded by prof. Holt. :)
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
Someone just recently explained to me how when electricity is running through a conductor a magnetic field is also present around the conductor. When you wrap that conductor up in a ball or a circle the magnetic fields are pressing up against each other which acts to slow down the flow of electricity through the conductor. If this conductor was feeding a light bulb there would be a delay before the light bulb comes on. Likewise when you disconnect the conductor from its power supply there is a delay before light bulb goes off.
I probably got that wrong but hopefully this paper's not being graded by prof. Holt. :)
The only big problem there is that the delay you are talking about would normally be a small fraction of a cycle at 50 or 60 Hertz, so you would not really notice it.
It is why there is a phase lag between the voltage and the current in an inductor or motor winding.
The idea of the fields pressing up against each other is not a perfect one either, since it would predict that you would see an effect at DC, and you do not.

What is actually happening is that the increase in the magnetic field generates a voltage in the opposite direction which tries to prevent the flow of current in the first place. But all it can do is slow down the rate of increase.
Nature may or may not abhor a vacuum, but it definitely resists change. :)
 

Ravenvalor

Senior Member
The only big problem there is that the delay you are talking about would normally be a small fraction of a cycle at 50 or 60 Hertz, so you would not really notice it.
It is why there is a phase lag between the voltage and the current in an inductor or motor winding.
The idea of the fields pressing up against each other is not a perfect one either, since it would predict that you would see an effect at DC, and you do not.

What is actually happening is that the increase in the magnetic field generates a voltage in the opposite direction which tries to prevent the flow of current in the first place. But all it can do is slow down the rate of increase.
Nature may or may not abhor a vacuum, but it definitely resists change. :)

So the inductor is resisting a change in current.

Not to stray off topic, a capacitor on the other hand stores electrons on 2 - plates separated by an insulator. One plate has a bunch of negatively charged electrons on it and the other plate is filled with positively charged electrons. In a simple circuit they act as a storage container which will delay the turning off and on of a light. They also resist electricity but not current only voltage.
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
So the inductor is resisting a change in current.
:thumbsup:

Not to stray off topic, a capacitor on the other hand stores electrons on 2 - plates separated by an insulator. One plate has a bunch of negatively charged electrons on it and the other plate is filled with positively charged electrons. In a simple circuit they act as a storage container which will delay the turning off and on of a light. They also resist electricity but not current only voltage.
Not bad, except there are no negatively charged electrons. Only places where the electrons have moved away leaving a net positive charge from the lonely atomic nuclei. There is probably a Country Western song lyric in there somewhere. :lol:
 

Ravenvalor

Senior Member
:thumbsup:


Not bad, except there are no negatively charged electrons. Only places where the electrons have moved away leaving a net positive charge from the lonely atomic nuclei. There is probably a Country Western song lyric in there somewhere. :lol:

Thanks for the correction. An electron is negative, a proton is positive and a neutron is neutral. Seems like Bill Nye the science guy can make up a song for this one.
 

Eddy Current

Senior Member
PS: This is one of those questions where I cannot tell without more interaction whether you are asking a meaningless question about a concept you do not understand or a really sophisticated one, so my answer may be somewhere in between too.

A little bit of both i suppose.
 

Ravenvalor

Senior Member
Correct. An inductor resists a change in current and a capacitor resists a change in voltage.

Our friend posted earlier that an inductor resists a change in current because the wound wire creates a magnetic field which generates voltage in the opposite direction that repels a change in current. I wonder if the capacitor plates creates something that generates current in the opposite direction that repels a change in voltage.
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
Our friend posted earlier that an inductor resists a change in current because the wound wire creates a magnetic field which generates voltage in the opposite direction that repels a change in current. I wonder if the capacitor plates creates something that generates current in the opposite direction that repels a change in voltage.
Not exactly.
What the plates do is provide such a low resistance to current flow that it is hard to build up a voltage until you gotten have the charge buildup to match.
 

John120/240

Senior Member
Location
Olathe, Kansas
Have never tried this so: Take a coil of 14 or 12 Romex & leave it coiled up.Connect one end to a power source. Connect the other end to a motor. When energized it is said to resemble an expanding slinky.
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
Have never tried this so: Take a coil of 14 or 12 Romex & leave it coiled up.Connect one end to a power source. Connect the other end to a motor. When energized it is said to resemble an expanding slinky.

I would expect that to happen very strongly if you run only one conductor (either hot or neutral) through the coil.
There could be a short range repulsion with both conductors used but not enough for a slinky.
I have not tried it though.
 
Status
Not open for further replies.
Top