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Proton passes parallel conducting plates

  1. Jan 25, 2010 #1
    A proton is shown to pass between two parallel conducting plates across which a steady potential difference is maintained. Its path curves upwards.

    An alpha particle enters at the same point with the same velocity as the proton. Add its path to the diagram. Why is it like this.

    The path is less curved, and the answer given is:

    Charge on alpha is double that on proton, so force is double using F=Eq

    Mass of a particle is (approx) 4 times more hence acceleration is approximately halved

    Why is the second point added? What has the acceleration got to do with the change in path? Is it that particles that deflect more have a greater acceleraton because their direction is changed?
  2. jcsd
  3. Jan 25, 2010 #2


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    Hi Masafi! :smile:
    Yes, it's like turning a car … the more acceleration, the tighter the circle.

    So the proton accelerates more than the alpha particle, and it turns tighter (more curved). :wink:

    (acceleration is change in velocity, and that of course includes change in direction, even if there's no change in speed :smile:)​
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