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Define electric resistance and write it's SI unit. How does the reisitance of a conductor vary if (a) conductor is stretched to 4 times of it's length (b) Temperature of a conductor is increased. |
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Answer» Solution :Electric (R ) : The resistance offered by a flow of electrons in a CONDUCTOR is called electric resistance. S.I unit of resistance is ohm `(OMEGA)` The resistance of a conductor `R = (rho l)/(A) = (rho l^(2))/(V) implies R PROP l^(2)` (a) In first CASE, `R_(1) = R, l_(1) = l` (b) In second case, `l_(2) = 4l, R_(2) = ?` `(R_(2))/(R_(1)) = (l_(2)^(2))/(l_(1)^(2)) implies (R_(2))/(R) = ((4I)/(I))^(2) :. R_(2) = 16 R` (b) Variation of resistance with temperature is given by `R_(t) = R_(0) (1 + alpha t)` If temperature increases, resistance also increases. |
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