1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Some more basic homework help

  1. Oct 28, 2003 #1
    some more basic homework help!!

    can you guys point me in the right direction, where to start? (grrr, so freakin lost in this class)

    11. A 22.5-eV positron (positively charged electron) is projected into a uniform magnetic field B = 455[mu]T with its velocity vector making an angle of 65.5 degrees with B (vector). Find (a) the period (b) the pitch p, and (c) the radius r of the helical path.

    ill try and scan the diagram too

    grr

    thanks

    im "learning" magnetic fields for this chapter.

    here is the scan of the problem, and a figure to go with it:

    [​IMG]
     
    Last edited: Oct 28, 2003
  2. jcsd
  3. Oct 28, 2003 #2
    was reading the chapter..and they had a section on circulating charges ... it had an equation relating qvB to centripetal acceleration of:

    qvB=m(v^2)/r

    problem is, in the question, to find r, we have to know v, which isnt given ?? and also, dont know the mass ?

    grrrrr

    any help!1??!
     
  4. Oct 28, 2003 #3
    I think you can find v from the energy of the positron by using the kinetic energy formula, since E = 22.5 eV << the positron rest mass (0.5 MeV). The mass is equivalent to the electron mass.
     
  5. Oct 29, 2003 #4
    ehh?

    is the kinetic energy formula:

    K=(1/2)mv^2 ?

    and still lost on this part:

    since E = 22.5 eV << the positron rest mass (0.5 MeV). The mass is equivalent to the electron mass.
     
  6. Oct 29, 2003 #5
    Yeah, that should be the right formula.

    A positron basically is just an electron with a positive charge, so they have the same mass.
     
  7. Oct 29, 2003 #6
    so whats the mass? 22.5 ??
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Some more basic homework help
  1. Some more help pls (Replies: 1)

  2. Some More Help Please (Replies: 0)

Loading...