Question

When 5 V potential difference is applied across a wire of length 0.1 m, the drift speed of electrons is `2.5 xx 10^(-4) ms ^(-1)`. If the electron density in the wire is ` 8 xx 10^(28) m^(-3)`, the resistivity of the material is close to :
A. `1.6 xx 10^(-6) Omega m`
B. `1.6 xx 10^(-5) Omegam`
C. `1.6 xx 10^(-8)Omega m `
D. `1.6 xx 10^(-7) Omega m`

Answer 1

Correct Answer - B
(b) `V= IR = (neAv_d)rho l/A`
`:. rho = V/(V_dline)`
Here V = potential difference
l = length of wire
n = no. of electrons per uint volume of conductor.
e = no. of electrons
Placing the value of above parameters we get resistivity .
`rho = (5/(8 xx 10^(28) xx 1.6 xx 10^(-19) xx 2.5 xx 10^(-4) xx 0.1))`
`= 1.6 xx 10^(-5) Omegam`