Menu
Home / General Knowledge / Physics :: Discussion

Discussion :: Physics

  1. A copper wire of radius r and length l has a resistance of R. A second copper wire with radius 2r and length l is taken and the two wires are joined in a parallel combination. The resultant resistance of the parallel combination of the two wires will be

    2. A.

     5 R
    B.

     5 R/4
    C.

     4 R/5
    D.

     R/5

    View Answer

    Workspace

    View Answer

    Answer : Option D

    Explanation :

    1st copper wire: R = pl/A = pl/ πr2
    2ndcopper wire: R’ = p’l’/A’ = pl/(4 πr2) = R/4
    If joined in parallel, (1/Req) = (1/R) + (1/R’)
    = 1/R + 4/R
    = 5/R
    Req = R/5

Write your comments here:

Be The First To Comment