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Homework Help: Left and Right Hand Rules - Physics

  1. Apr 28, 2005 #1
    Hello Everyone,

    I am having trouble with the left and right hand rules in Physics. If anyone could explain them to me with as much detail as possible I would really appreciate it. I can tell you what I know and some of what I would like to know if it helps:

    The left hand is used for electron flow. Electrons flow from negative to positive and this is the direction that your thumb should point. Your fingers curl up and over the wires to give you the direction of the magnetic field.

    The right hand is used for conventional current which flows from positive to negative, your thumb points in the direction of this. Your fingers curl up and over the wires to give you the directoin of the magnetic field.

    Here is some of what I want to know. How do you tell which end of the wire is north and south? When is it best to use what rule? And anything else you can give me, I am so lost right now :cry:
  2. jcsd
  3. Apr 28, 2005 #2
    When you know what type of current it is, use the correct hand. Thats all there is to it.
  4. Apr 28, 2005 #3
    But how do you figure out which end of a wire is north and which is south?
  5. Apr 28, 2005 #4
    Wires dont have a north end or south end.. the problem will tell you that current is flowing in a direciton, if it says the current is electrons, then use the left hand, if its the ocnventional current, use the right hand.

    If its from a circuit diagram, then decipher the current flow from the configuration of the circuit, namely the EMF.
  6. Apr 29, 2005 #5

    James R

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    Forget left hand rules. Always use the direction of conventional current, and remember that if the charge carriers are negative the conventional current flows the opposite direction to the way the charges move.
  7. Apr 29, 2005 #6
    the right hand rule is for EM induction, and left hand is the motor rule. Always use conventional current for both.
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