1. Limited time only! Sign up for a free 30min personal 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!

Homework Help: Resistance of a piece of metal

  1. Mar 7, 2010 #1
    1. The problem statement, all variables and given/known data

    How does the resistance of a piece of metal change if both its length and its diameter are reduced to one half their original values?
    Question 1 answers
    It is increased to 4 times the original value
    It doubles
    It remains unchanged
    It is halved
    It is reduced to 1/4 of the original value

    2. Relevant equations

    R = pL/A where P is the resistivity constant

    3. The attempt at a solution

    I am not sure how to relate the area to change in area
  2. jcsd
  3. Mar 7, 2010 #2
    Re: Resistance

    I think you can assume it's a round wire.
  4. Mar 7, 2010 #3


    User Avatar
    Homework Helper

    Re: Resistance

    they call one dimension a "diameter" , which becomes half
    ... how does the new Area compare to the old Area ?
    (it's not about _change_ , it is about new = "some number" times old)
  5. Mar 7, 2010 #4
    Re: Resistance

    Assume it's a round wire, with diameter d, the new diameter will be d/2.
    old length is L, new length is 2L

    Calculate old and new resistance, compare.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook