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I am confused about the right-hand rule for the Lorentz force. I am using same method as Brightstorm.com is:

http://www.youtube.com/watch?v=LK7hv4LX3ys

But for some reason it does not match op with this example from my book.

Right hand rule exampld

Could someone explain to me what I am doing wrong?

I first curl my finger around the wire so as the current is going downwards.

But since the charge is moving upwards, I need to flip my hand upwards, but that flips the curl, and thereby the direction of the $B$-field. What am I doing wrong?

Qmechanic
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user26022
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2 Answers2

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note that the charge is negative!

httplistener
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Starting with equation $F=v \times B$ I visualize the vector v pointing up, and traveling (rotating) the shortest arc to the B vector, which is pointing into the page, v and B now define a plane. The direction the vector v takes is counter-clockwise or clockwise depending on what side of the plane you are looking at, so I visualize a right-handed screw along that normal axis (that vector F will lie along) and imagine what direction that screw will travel if it turns along with vector v. Then in your case you have a negative charge which changes the sign of F. I'm sure there are many different and more elegant ways to calculate it, but that is what I think of to double-check.

walczyk
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