InterviewSolution
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InterviewSolution
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The number density of free electrons in a copper conductor as estimated is 8.5xx 10^28 m^(-3) . Howlong does an electron take to drift from one end of a wire 3.0 m long to its other end ? The areaof cross-section of the wire is 2.0 xx 10^(-6) m^2and it is carrying a current of 3.0 A. |
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Answer» Solution : Here number density of free ELECTRONS `N = 8.5 xx 10^28 m^(-3)`, length of wire l = 3.0 m, cross-section area`A = 2.0 xx 10^(-6) m^2` and I = 3.0 A From the relation I=ne `A v_d`, we have `v_d = (I)/("neA") = l/t` where t is the time taken by free electrons to DRIFT from one end of conductor to the other end `t = ("neAl")/(I) = (8.5 xx 10^28 xx 1.6 xx 10^(-19) xx 2.0 xx 10^(-6) xx 3.0)/(3.0) = 2.72 xx 10^4 s` ` = (2.72 xx 10^4)/(60 xx 60) h = 7.5 h (appx)` |
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