Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Just To Double Check

  1. Jan 25, 2005 #1
    Just two questions that are a small part of my ISU for physics. For this year we had to teach ourselves the unit on electricity and magnetism.

    1. A bird stands on an electric tranmission line carrying 1200A. The line has a [itex]1.0\times10^{-5} \Omega[/itex] resistance per metre and the bird's feet are 30cm apart. What voltage does the bird feel.

    2. What is the force per metre on a wirde carrying a 2.50A current when perpendicular to a 1.10T magenetic field.

    For question one, I was first thinking that since the bird isn't grounded, it shouldn't really feel anything, but since the question probably wouldn't be as easy as that, i guess i'd have to calculate something.

    Formula i used was just V=IR
    [itex]V = (1200 A)(1.0\times10^{-5} \Omega)(3.0\times10^{-1}m)= 3.6 \times 10^{-3} V
    [/itex]

    That's what i got as a final answer

    For question two, our books didn't really mention anything about formulas with the tesla unit so i guess we had to research it.

    I found a formula that was :

    [itex]B=\frac {F} {IL} \vspace[/itex]

    B is 1.10T
    I is 2.50 A
    L i think would be 1m since they wanted the force per metre.
    F is the unkown

    So in the end i got [itex]F = BI

    = 1.10T \times 2.50A =2.75 N/m
    [/itex]

    Just need some feedback on those questions.
     
    Last edited: Jan 25, 2005
  2. jcsd
  3. Jan 25, 2005 #2
    good job :tongue:
    i didn't check your number, but you have applied the formulas correctly
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook