Question
Tue July 10, 2012 By: Arun Deepak Tirkey
 

Two wires A and B are of equal lengths,different cross sectional areas and made of same metal. (A)(i)Name the property which is same for both the wires (ii)Name the property which is different for both the wire. (B)If the resistance of wire A is four times the resistance of wire B,calculate(i)the ratio of the cross sectional areas of the wire (ii)the ratio of the radii of the wires.

Expert Reply
Wed July 11, 2012
(A) (i) THe resistivity being the property of the material will be same.
      (ii) Resistance being the property of gometry of conductor will be different.
 
(B) (i) Resistance is inversely proportional to the area of cross section of the conductor.
          Thus since the resistance of A is 4 times the resistance of B, hence the ratio of area of
          cross-section of A to B will be 1:4
      (ii) Ratio of radii of wire is square root the ratio of area (because r=?A/pi) thus ratio of radii
           will be 1:2
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