A wire of length L and resistance R is stretched so that its length is doubled and the area of cross-section is halved

CBSE Class 10 CBSE Class 10 Science
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1

A wire of length L and resistance R is stretched so that its length is doubled and the area of cross-section is halved. How will its:

  1. resistance change?
  2. resistivity change?
    Justify your answer in each case.

Answer:

  1. Here, length is doubled and area of cross-section is halved. Thus, a wire of length l and area of cross-section A becomes a wire of length 2l and area of cross-section A/2
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    i.e., resistance becomes four times
  2. Resistivity of a substance does not depend on its length or area of cross-section. It depends on the nature of the material and temperature. Hence there is no change