Mysterious magnetic force!If you have a loop in which current goes clockwise as seen from top, then it forms a north pole if seen from below. Now if a particle with positive charge goes from left to right under it, it experiences and upward force, now if the 1st loop was very large and particle goes from near about the axis of loop, it goes in a circle in anti-clockwise direction as seen from the top. This again generates a north pole if seen from top.Q1. Since we have two north poles facing each other, why don't we get a new repulsive magnetic force?If you closely observe this systen then the negative charges travelling in 1st loop in anti-clockwise direction have synchronized with the positive charge going anti-clockwise below it. Not only this, if you send the particle from right to left, it experiences a downward force and again synchronizes, now again if you try sending negative particles they get synchronized in the same way with the positive particles.Q2. Why is such a synchronizing taking place?I am more interested in the first question for now, as I am trying to work out the second problem myself.

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Mysterious magnetic force!If you have a loop in which current goes clockwise as seen from top, then it forms a north pole if seen from below. Now if a particle with positive charge goes from left to right under it, it experiences and upward force, now if the 1st loop was very large and particle goes from near about the axis of loop, it goes in a circle in anti-clockwise direction as seen from the top. This again generates a north pole if seen from top.Q1. Since we have two north poles facing each other, why don&#039;t we get a new repulsive magnetic force?If you closely observe this systen then the negative charges travelling in 1st loop in anti-clockwise direction have synchronized with the positive charge going anti-clockwise below it. Not only this, if you send the particle from right to left, it experiences a downward force and again synchronizes, now again if you try sending negative particles they get synchronized in the same way with the positive particles.Q2. Why is such a synchronizing taking place?I am more interested in the first question for now, as I am trying to work out the second problem myself.

Maeve Holloway · Accepted Answer

Question 1:Let&#039;s treat the particle (assuming positively charged; just flip the directions for negative charges) as if it&#039;s at the axis (or very, very close to it, compared to the radius of the loop). Then the magnetic field of the loop is pointing down (away from the center of the loop, towards the particle), so the force on the particle (right hand rule) is into the page. This causes the particle to move in a circle in a plane parallel to the plane containing the first loop, but in the opposite direction. Then the particle generates it&#039;s own magnetic field. This field is pointing up on the axis of the particles&#039;s loop, but then curls away from the axis to wrap around underneath (this is the magnetic field of a dipole, I&#039;m sure you&#039;ve seen a picture of it). Then at the loop itself, the magnetic field has a radial component and a vertical component. The vertical component causes a radial force on the loop; this cancels because each part of the loop has force equal and opposite to the part of the loop directly opposite it. The radial component of the magnetic field induces a downward force, pulling the loop towards the particle. So in total we have a magnetic force on the particle pushing it in a circle, and a magnetic force from this circle on the loop pulling it towards the particle. There are higher order corrections that can be made based on the magnetic field caused by the current loop accelerating downward, but those are usually quite small. There isn&#039;t an upward force on the particle; Newton&#039;s third law doesn&#039;t apply directly to magnetic forces, because they don&#039;t act along the line connecting the charges. In trying to understand magnetic fields and forces, I would advise staying away from the &quot;North pole/South pole&quot; idea and instead work with vectors, because then there is less possibility for a conceptual error (just make sure to keep track of minus signs).ADDED: Question 2:I don&#039;t think &quot;synchronizes&quot; is the right word here. The charges are not necessarily moving at the same angular velocity as the particle; they are almost certainly slower. They do circle in the same direction, if you assume that both positive and negative charges are moving in the loop (this is possible, e.g., in plasmas, but in wires it is just the negative ones). Did you mean something else by &quot;sychronized&quot;?

Mysterious magnetic force! If you have a loop in which current goes clockwise as seen from top, th

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