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The resistance of eureka wire is `2.5 Omega`. What is the value of specific resistance of write of 14 m length and diameter of 0.14 cm ?A. `27.5xx10^(-6)Omega - cm`B. `20.6xx10^(-6)Omega - cm`C. `25.3xx10^(-6)Omega - cm`D. None of the above |
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Answer» Correct Answer - A Length of wire, `l=14 mxx100=1400 cm` Diameter of wire = 0.14 cm `therefore " "` Radius of wire `r=(0.14)/(2)=0.07 cm` Cross-sectionl area of wire `= pi r^(2)=pi(0.07)^(2)` Resistance of wire `= 2.5 Omega` By formula, `R = rho (l)/(A)` `rArr " " rho=(AR)/(l)=(pixx(0.07)^(2)xx2.5)/(1400)` `" " = (pixx0.07xx0.07xx2.5)/(1400)` or `" " rho = 27.5xx10^(-6)Omega - cm` |
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