It is desired to make a long cylindrical conductor whose temperature coefficient of resistivity at `20^(@)C` will be close to zero. If such a conductor is made by assembling alternate disks of iron and carbon, find the ratio of the thickness of a carbon disk to that an iron disk. `("For carbon", p = 3500 xx 10^(-8)Omega m and alpha= -0.50 xx 10^(-3) .^(@)C^(-1) "for iron, p"=9.68 xx 10^(-8)Omega m and alpha=6.5 xx 10^(-3).^(@)C^(-1))`A. 0.36B. 0.036C. 1D. 2

It is desired to make a long cylindrical conductor whose temperature c

1.	It is desired to make a long cylindrical conductor whose temperature coefficient of resistivity at `20^(@)C` will be close to zero. If such a conductor is made by assembling alternate disks of iron and carbon, find the ratio of the thickness of a carbon disk to that an iron disk. `("For carbon", p = 3500 xx 10^(-8)Omega m and alpha= -0.50 xx 10^(-3) .^(@)C^(-1) "for iron, p"=9.68 xx 10^(-8)Omega m and alpha=6.5 xx 10^(-3).^(@)C^(-1))`A. 0.36B. 0.036C. 1D. 2
Answer» Correct Answer - B The direction of currently density is the direction of flow of positive charge in the circuit which is possible due to electric field produced by charges accumulated on the surface of wire.

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