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Homework Help: Proton in magnetic and electric field

  1. Oct 24, 2011 #1
    1. The problem statement, all variables and given/known data


    As shown in the figure below, a proton moves in the +x direction with speed v and is immersed in both, a uniform magnetic field, B, oriented in the -z direction, and a uniform electric field, E (not shown in the diagram). What electric field orientation is required in order for the proton to move un-deflected through the combined magnetic and electric field region?
    (a) +y direction
    (b) -y direction
    (c) +z direction

    Answer is B.

    http://i.imgur.com/1G80T.png

    1G80T.png

    2. Relevant equations

    qE=qVB

    3. The attempt at a solution

    I used RHR, I get answer A...
     
  2. jcsd
  3. Oct 24, 2011 #2

    Delphi51

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    Homework Helper

    Which way does the B field push on the proton?
    Which way should the E field push on it?
     
  4. Oct 25, 2011 #3
    Which way does the B field push on the proton? Along x-axis
    Which way should the E field push on it? Opposite direction of qvb?
     
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