A copper wire has diameter 0.5mm and resistivity of 1.6xx10^(-8)Omegam – InterviewSolution

1.	A copper wire has diameter 0.5mm and resistivity of 1.6xx10^(-8)Omegam. what will be the length of this wire to make its resistance 10Omega? How much does the resistance change if the diameter is doubled ?
Answer» SOLUTION :`d=0.5mm=0.5xx10^(-3)m,P=1.6xx10^(-8)Omegam` `R=10Omega,l=?` `R=rhol/Atol=(RA)/rho` Therefore `l=(10xx22xx0.5xx0.5xx10^(-6))/(7xx4xx1.6xx10^(-8))=122.65m` If the diameter is doubled, then RESISTANCE BECOMES one FOURTH.

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