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Cathode Rays Experiment some missunderstood parts

  1. Jul 20, 2010 #1
    Hi all

    I don't know If this is the suitable section for this post.. but at all.. let's see if any body can make me understand this :):)

    You all know of course J.J. Thomsons's three CRT experiments...

    The first one was aiming to prove that the appearing rays and the negative charges detected by the electrometer are inseperable and interwined, and that was by exposing them to a magnetic field, observed that the rays were bent and no readings were recorded on the electrometer.. so they proved it well... but please.. isn't that meaning that the rays carry -ve charge?? so what's the aim of the 2nd exp.?????
    My personal understanding is that the 2nd exp. is to find a solution for the problem of rays being not deflected by electric field and not to prove anything.. BUT

    In the second exp. Thomson found a solution for the problem and -I don't know how..- he concluded that the rays are particles -vely chraged... How this differs from the first exp. Does the magnetic field differs physically from the electric field -I mean in attracting charged bodies-? doesn't the attraction by magnet prove that the rays are -vely chraged particles??

    I'm Waiting ;)
  2. jcsd
  3. Jul 21, 2010 #2
    The second experiment proved that the rays were deflected by an electric field.
    Other workers had failed to find this - leading them to believe that the beam perhaps did not consist of charged particles.

    Thompson's first experiment showed that the beam produced charge at the electrometer - it did not prove that the charge was carried by the beam.
    The second confirmed that the beam itself carried charge.
    The third allowed him to actually calculate the ratio of mass to charge of the particles in the beam. Showing in fact that they were particles.
  4. Jul 21, 2010 #3
    Thank You very very much.. I'm very grateful to u
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