A resistance wire made of German silver has a resistance of 4.2 . Calculate the resistance of another wire made of the same material, such that is length increasesBy 4 times andThe area of cross section decreases by 3 times.
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Answer:
RI = 4.25 lI = l (say)
R2 = ? a1 = a (say)
L2 = 4 l
a 2 = a/3
As both the wires are made of the same material, have same sp. Resistance
∴ P = R1a1/l1 = R2a2/l2
Or R2 = R1a/l × 4l/(a/3)
∴ R2 = 12R1 = 12 × 4. 25 = 51.00 Ω
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