A material B has twice the specific resistance of A. A circular wire made of B has twice the
diameter of a wire made of A. Then for the two wires to have the same resistance, the ratio
LB : LA of their respective lengths must
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3
Answer:
2 : 1
Explanation:
R = pL/A
we get p = RA/l = Rπd^2/4l
l = Rπd^2/p
l is proportional to d^2/p
lA/lB = d^2/p/4d^2/2p = 1/2
then,lA/lB = 2 : 1
hence the ans is 2 : 1
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