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: Electrical conduction

  1. Sep 8, 2004 #1
    figure show 2 ways how 2 thin nichrome wires P and Q at fixed p.d. V are connected. Both P and Q are of the same length but the diameter of wire P is bigger than that of wire Q. When wire P and Q glow steadily in both circuit, which on of the following shows the comparison of brightness between wire P and Q in each connection?

    for series connection, i know that Q is brighter than P because p.d. across Q is greater ( resistance Q > resistance P )

    for bout the parallel connection? i thought the brightness of P and Q should be same because p.d. across both P and Q are same
    but answer is P brighter than Q.
    any clue?

    and am i correct to compare brightness by comparing the p.d. ?
     

    Attached Files:

    Last edited: Sep 8, 2004
  2. jcsd
  3. Sep 8, 2004 #2

    ehild

    User Avatar
    Homework Helper

    No. You should compare power, P=U*I. (voltage * current)

    ehild
     
  4. Sep 8, 2004 #3
    thanks ehild.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook