Why do wires attract each other when current flows in the same direction?

In summary, the question is about the behavior of parallel wires carrying current. It is observed that when the current is flowing in the same direction, the wires attract each other. This can be explained by the fact that the magnetic field lines of the two wires are in the same direction, resulting in attraction. This phenomenon is not seen in a single wire due to the absence of a second wire with a magnetic field. The terms "north" and "south" are not applicable in this case and are only used as a convenience for larger bodies. The magnetic field is continuous and has a circular direction, determined by its handedness.
  • #1
Jack98
4
1
Hi all, the question is in regards to magnetic fields in a wire. Please refer to illustration below to understand my question.
(https://www.imageupload.co.uk/image/B9f1)

As you can see in Picture 3 two wires parallel to each other will attract each other if the current is going in the same direction. How does attraction occur? Why don't the wires repel each other since the wire acts like a magnet with the same dipoles parallel to other. For example. t's like 2 magnetic dipoles north and south parallel to each other.

If we apply this same scenario but the wire is a magnet on a horizontal plane it makes sense but as you can see in picture 1 this is not correct. In picture 1 if the wire was a magnet on a horizontal plane why doesn't it show the results of picture 2?

Thank you in advance and sorry if it's a silly question. I'm really struggling figuring it out and I know there are smart people on this forum.
 
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  • #2
Welcome, @Jack98 to Physics Forums!

Your curiosity for getting the answer to this question is genuine and I appreciate your concern.

We, in here, try to answer such questions and support the various concepts regarding a specific subject.
And you are fortunate enough to know that, we have already attempted to answer to this question.
I am giving you the link of one of the thread of PF(PhysicsForums) discussing the answer to the same question.
Here it is,

https://www.physicsforums.com/threads/why-do-parallel-currents-attract.39472/

I would suggest, to read all the thread replies for understanding this concept in detail.
:thumbup:
 
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  • #3
Wires carrying current have no recognised N or S poles, the force lines go around the wires.
 
  • #4
Yeah, I think the source of the confusion here is that you treat "north" and "south" as actual entities, whereas they are just convenient simplifications of the (usual) bar-type magnet.

There is no start or end to a magnetic field, all field lines are closed loop. So, what really matters when it comes to attraction/repulsion is whether the field lines of the two magnetic fields meet head-on (repulsion) or are in the same direction (attraction).
 
  • #5
Shubham Jaydeokar said:
Welcome, @Jack98 to Physics Forums!

Your curiosity for getting the answer to this question is genuine and I appreciate your concern.

We, in here, try to answer such questions and support the various concepts regarding a specific subject.
And you are fortunate enough to know that, we have already attempted to answer to this question.
I am giving you the link of one of the thread of PF(PhysicsForums) discussing the answer to the same question.
Here it is,

https://www.physicsforums.com/threads/why-do-parallel-currents-attract.39472/

I would suggest, to read all the thread replies for understanding this concept in detail.
:thumbup:

Thank you very much for the link you provided. I hope I find answers to my question.
 
  • #6
lychette said:
Wires carrying current have no recognised N or S poles, the force lines go around the wires.
Why do compasses show a wire has magnetised dipoles? I'm really confused. I understand magnetic fields are a concept.
 
  • #7
rumborak said:
Yeah, I think the source of the confusion here is that you treat "north" and "south" as actual entities, whereas they are just convenient simplifications of the (usual) bar-type magnet.

There is no start or end to a magnetic field, all field lines are closed loop. So, what really matters when it comes to attraction/repulsion is whether the field lines of the two magnetic fields meet head-on (repulsion) or are in the same direction (attraction).

That makes good sense and it's help me further understand magnetism but don't we represent the rotation of the fields as north or south? For example the north field lines are attracted to the south pole in a closed loop. Electric charge fields can be both monopole and dipoles but magnetic fields can only be dipoles does current going through a single wire have dipoles or is it a mono pole? Solenoids is a magnetic dipole and it's easier for me to visualise and understand then a single wire, which I can't wrap my head around.
 
  • #8
I find the use of the term "dipole" entirely misleading when it comes to magnetism.

As you yourself found out, "North" and "South" don't make much sense when it comes to wires. That's because those terms are kinda shoddy, and only serve as a convenience for when a massive body generates a magnetic field. Where the magnetic fields exit the body people call it "North", where it reenters it's called "South". But of course the magnetic field continues inside the body. So, what's special about those two ends? Nothing really. You could see shave off a centimeter at the ends of a bar magnet, and have new North and South ends.

All that matters are the circular field lines. And the direction of them is defined through their "handedness", either right handed or left handed.
 

FAQ: Why do wires attract each other when current flows in the same direction?

1. What is a magnetic field?

A magnetic field is a region in space where a magnetic force can be detected. It is created by the movement of electrically charged particles, such as electrons.

2. How is a magnetic field around a wire created?

When an electric current flows through a wire, it creates a circular magnetic field around the wire. The strength of the magnetic field depends on the amount of current flowing through the wire.

3. How does the direction of the current impact the magnetic field around a wire?

The direction of the current determines the direction of the magnetic field. The magnetic field lines around a wire will flow in a counter-clockwise direction for a current flowing in one direction, and in a clockwise direction for a current flowing in the opposite direction.

4. Can the strength of the magnetic field around a wire be changed?

Yes, the strength of the magnetic field can be changed by altering the amount of current flowing through the wire. Increasing the current will increase the strength of the magnetic field, while decreasing the current will decrease the strength of the magnetic field.

5. How does the distance from the wire affect the strength of the magnetic field?

The strength of the magnetic field decreases as the distance from the wire increases. This is because the magnetic field lines spread out as they move away from the wire, resulting in a weaker field at a greater distance.

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