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A wire of silver has a resistance of 1 ohm. Specific resistance of constantan is 30 times the specific resistance of silver. Find the resistance of a constantan wire whose length is one third length of the silver wire and radius half the radius of the silver wire. |
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Answer» Solution :`R_s = 1 OMEGA, rho_C = 30 rho_s` Resistance of constantan `R_C =?` Length `l_c =(l_s)/(3)` radius `r_s = 2r_c` We know that `R=(rhol)/(a) = (rhol)/(pir^2)` `(R_c)/(R_s) = (rho_c)/(rho_s) (l_c)/(l_s) ((r_s)/(r_c))^2 = (30)/(3) xx 4 = 40` Resistance of constantan `R_c = 40 xx 1 = 40 Omega` |
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