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Question
When 5 V potential difference is applied across a wire of length 0.1 m, the drift speed of electrons is 2.5 x 10-4 m/s. If the electron density in the wire is 8 x 1028 m-3, calculate the resistivity of the material of the wire.
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Solution
The drift speed is
`v_d=I/(`
Now, we know that the current is given from Ohm’s law as
`I=V/R`
`:.v_d = V/`
`:.V/(`
`=>V/(`
Now, resistivity is given as `rho=(RA)/l`
`:.V/(`
`:.rho=5/(8xx10^28xx1.6xx10^(-19)xx2.5xx10^(-4)xx0.1)`
∴ ρ = 1.56 x 10-5 Ωm
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