Hello there,

Here's a simple magnetic force question.

We have a uniform magnetic field B pointing into the page, perpendicular to the page.

We have a wire running across the page with current flowing from left to right, using positive conventional current flow so the current flows from left to right and it is comprised of positive charges (not negative charges like electrons). This wire is perpendicular to B.

The wire is free to move (the whole wire can drift not just one part of it) and the B field is directed in such a way that it exerts a force on the wire, so the wire gets deflected.

The question is, in which direction does the wire get deflected?

A search around the web will show that a technique known as the "Right Hand Rule" can be used. It will also show that on one web site we will end up finding that the wire gets deflected upward, while on another web site we will have to conclude that the wire will get deflected downward. The mix up might come from the fact that one web site states that the index finger points in the direction of current I and middle finger in the direction of B, while another states that the index finger points in the direction of B and the middle finger in the direction of I. Swapping fingers like that means the direction of the force gets reversed, so one way we get "up" and the other way we get "down" where the direction of the force is indicated by the thumb.

This is pretty amazing that such a simple concept can be so skewed, and probably not presented correctly in the first place.

So which would you choose, "up" or "down" (or even some other direction), and what theory do you have that backs that claim up? Please feel free to use any math technique you like, if you choose to do so.

I would like to hear any arguments really, with math or not. Try first to use the Right Hand Rule.

Also important, how would you suggest orientating the fingers in the Right Hand Rule above?

Thanks

Here's a simple magnetic force question.

We have a uniform magnetic field B pointing into the page, perpendicular to the page.

We have a wire running across the page with current flowing from left to right, using positive conventional current flow so the current flows from left to right and it is comprised of positive charges (not negative charges like electrons). This wire is perpendicular to B.

The wire is free to move (the whole wire can drift not just one part of it) and the B field is directed in such a way that it exerts a force on the wire, so the wire gets deflected.

The question is, in which direction does the wire get deflected?

A search around the web will show that a technique known as the "Right Hand Rule" can be used. It will also show that on one web site we will end up finding that the wire gets deflected upward, while on another web site we will have to conclude that the wire will get deflected downward. The mix up might come from the fact that one web site states that the index finger points in the direction of current I and middle finger in the direction of B, while another states that the index finger points in the direction of B and the middle finger in the direction of I. Swapping fingers like that means the direction of the force gets reversed, so one way we get "up" and the other way we get "down" where the direction of the force is indicated by the thumb.

This is pretty amazing that such a simple concept can be so skewed, and probably not presented correctly in the first place.

So which would you choose, "up" or "down" (or even some other direction), and what theory do you have that backs that claim up? Please feel free to use any math technique you like, if you choose to do so.

I would like to hear any arguments really, with math or not. Try first to use the Right Hand Rule.

Also important, how would you suggest orientating the fingers in the Right Hand Rule above?

Thanks

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