We know i=neAvd
⇒i=RV=ρlVA=ρEA
ρ=iEA=neAvdEA
Drift velocity can be written as vd=meeEτ
ρ=neAeEτEAme=ne2τme
=8.5×1028×(1.6×10−19)2×25×10−159.1×10−31
≈1.65×10−8Ωm
JEE Main 2019 — Physics Electromagnetism
In a conductor, if the number of conduction electrons per unit volume is 8.5×1028m−3 and mean free time is 25fs (femto second), it’s approximate resistivity is: (me=9.1×10−31kg)
Held on 9 Apr 2019 · Verified 6 Jul 2026.
10−7Ωm
10−6Ωm
10−5Ωm
10−8Ωm
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