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Question:

In a conductor, if the number of conduction electrons per unit volume is 8.5 × 10^28 m⁻³ and mean free time is 25 fs (femtosecond), it's approximate resistivity is?

10⁻⁷Ωm

10⁻⁵Ωm

10⁻⁶Ωm

10⁻⁸Ωm

Solution:

Correct option is D. 10⁻⁸Ωm
ρ = m/ne²τ = 1.67 × 10⁻⁸Ωm.