(a) Write the relationship between resistivity and resistance of a cylindrical conductor of length l andβ¦
(a) Write the relationship between resistivity and resistance of a cylindrical conductor of length l and area of cross-section A. Hence derive the SI unit of resistivity. (b) Why are alloys used in electrical heating devices ?
Solution
(a)
π
β’ R=π
π΄
π π΄
ο²=
π
πβπ Γ (πππ‘ππ)2
β’ SI unit of ο² =
πππ‘ππ
= ohm meter
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(b) Resistivity of alloy is higher than pure metals. / They do not
oxidise (burn) readily at high temperatures.