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(a) (i) Due to change in length and area of cross-section of a conductor, resistance of conductor changes while resistivity does not change. Why?
(ii) Conductors of electric toasters and electric iron are made of an alloy rather than a pure metal. Why ?
(iii) Define the S.I. unit of electric current.
(ii) Conductors of electric toasters and electric iron are made of an alloy rather than a pure metal. Why ?
(iii) Define the S.I. unit of electric current.
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(a)
(i) As Resistance, $R = \rho \frac{l}{A}$, it changes with change in length and
area of cross section of conductor.
But resistivity of conductor is the characteristic property of
material and hence it does not change. (1)
(ii) The resistivity of an alloy is generally higher than that of its
constituent metals. /
Alloys do not oxidise (burn) readily at high temperatures. (1)
(iii) 1 Ampere is constituted by the flow of 1 Coulomb of
charge per second. /
$1\text{A}=1\text{C}/1\text{s}$ (1)
(i) As Resistance, $R = \rho \frac{l}{A}$, it changes with change in length and
area of cross section of conductor.
But resistivity of conductor is the characteristic property of
material and hence it does not change. (1)
(ii) The resistivity of an alloy is generally higher than that of its
constituent metals. /
Alloys do not oxidise (burn) readily at high temperatures. (1)
(iii) 1 Ampere is constituted by the flow of 1 Coulomb of
charge per second. /
$1\text{A}=1\text{C}/1\text{s}$ (1)