If an inductor is placed across a battery (or any dc power source) will its negative pole be the one closest to the negative terminal? Or is it the opposite? Thanks in advance!
Ah I think I realized now that the negative pole is the one closest to the negative terminal... as evidenced by if it were taken off the supply voltage the induced field would collapse in the same direction the current was traveling. Ay?
It depends what you mean by its negative pole. Also, inductors generate an EMF in response to a changing current through them. The polarity of that EMF depends on how the current is changing.
No! The reason being that which pole is closer has no effect on whether the coils of the inductor are wound clockwise or counterclockwise. I assume that by negative pole your mean south pole. Refering to a pole of an inductor as positive or negative has no particular meaning.
Thanks guys!!! This raises another question for me that I tried to google but couldn't find anything due to a huge amount of synonyms. What are the characteristics that distinguish a north pole from a south pole in a magnet? (specifically an electromagnet although I'm not sure if this makes a difference for the question)
A north pole will attract the south pole of another magnet and repel a north pole. In terms of the field, magnetic field lines head outwards from a north pole and into a south pole. Does that answer your question?
So the north pole could be looked at as the "negative" pole then right? Because it's almost like the negative terminal of a battery since the electrons flow away from it and towards the south or "positive" pole. Now what's confusing is that if the north pole is the one closest to the negative terminal of a battery, then it wouldn't really make sense to orient it that way because then you have electrons heading toward a negative pole. Also is there any validity to kevinalm's claim that the clockwise and counterclockwise orientation of an inductor is what determines the poles?
Common coils and resistors aren't assigned positive or negative ends. You may find this whole page interesting. Fig. 30.4 is the most relevant. http://www.physics.sjsu.edu/becker/physics51/induction.htm
Sorry to have to tell you, but the simple fact is your thinking about electromagnets all wrong. Look at it this way. The current in the coils of a solenoid is equivalent to a sheath of charge spinning around the axis of the solenoid. Which pole is at which end depends entirely upon the sign of the charge and the direction (clockwise or counterclockwise) of the spin. Which battery pole happens to be closer is completely irelavent. Also, it is totally wrong to call a magnetic pole positive or negative. This is meaningless. One says North or South pole (meaning North seeking pole or South seeking pole).
No. Electrons don't flow towards or away from either pole. Magnetic fields are not electric fields. No. (see above) Yes. Magnetic fields are created by the movement of charges - in your case, current flowing through a wire. The direction of current through the loop determines the direction of the resulting magnetic field. Reverse the direction in the loop by winding the loop the other way and you reverse the resulting field.
Thanks for the input kevinalm, I think I'm starting to get it. What do you mean by "sign of the charge" here?
If you look up the left hand rule for magnetism you will get some idea of the relationships between electricity and magnetism. Current flow is actually perpendicular to the moving magnetic field or moving current carrier. Like this: Please Register or Log in to view the hidden image!
The magnets have two poles. By convention they are called North pole and South pole. The poles are determined by two things. The direction of electricity, and the sense of coil turns. In total four possible cases. ( Left hand-rule ) Please Register or Log in to view the hidden image!
In electronics it is common to speak of "conventional current". This is simply an acknowledgement of the fact that positive charge carriers moving one way is completely indestinguishable from negative charge carriers moving the opposite direction. That is what I was refering to by "sign of the charge".
