Current Electricity 1 Question 2

2. A current of 5 A passes through a copper conductor (resistivity =1.7×108Ωm ) of radius of cross-section 5 mm. Find the mobility of the charges, if their drift velocity is 1.1×103m/s.

(2019 Main, 10 April I)

(a) 1.5m2/Vs

(b) 1.3m2/V-s

(c) 1.0m2/Vs

(d) 1.8m2/V-s

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Solution:

  1. Given,

I=5A,ρ=1.7×108Ωm,r=5mm=5×103m,vd=1.1×103m/s

Mobility of charges in a conductor is given by

μ=vdE

and resistivity is given by

ρ=EJ=EI/A(J=σE=1ρ×E)ρ=EAI or E=ρIA

From Eqs. (i) and (ii), we get

μ=vdAρI

Substituting the given values, we get

=1.1×103×π×(5×103)21.7×108×5=86.35×1098.5×108=10.1×101μ1m2/Vs



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