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A wire of resistance 10 ohm is drawn out of so that the length is 3 has its original line calculate its new resistance
Asked by sandhushivanand2004 | 27 Dec, 2019, 20:28: PM
answered-by-expert Expert Answer
when the wire is drawn out so that its length increases 3 times of its original length L, its initial cross scection area A decrases.
 
Since volume is constant,  L×A = 3L×An .......................(1)
 
where An is crosssection of wire after its length increased.
 
From eqn.(1), we get An = A/3
 
Let ρ be the resitivity of material of wire.
 
Hence changed resistance, Rn = ρ ×(3L)/ (A/3)  = 9 (ρ L / A ) = 9 × 10 = 90 Ω
Answered by Thiyagarajan K | 28 Dec, 2019, 08:56: AM

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