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Calculate the relaxation time and mean ...

Calculate the relaxation time and mean free path at room temperature (i.e. `27^(@)C`). If the number of free electrons per unit volume is `8.5 xx 10^(28)//m^(3)` and resistivity `rho = 1.7 xx 10^(8) Omega-m`. Given that mass of electron `= 9.1 xx 10^(-31) kg`
`e = 1.6 xx 10^(-19)C and k = 1 .36 xx 10^(-23) JK^(-1)`

A

`10^(-8) Omegam`

B

`10^(-7) Omega`m

C

`10^(-6) Omegam`

D

`10^(-5) Omega m`

Text Solution

Verified by Experts

The correct Answer is:
A
`sigma =("ne"^(2)C)/m_(e) rArr rho =m_(e)/("ne"^(2)C)`
`=(9.1 xx 10^(-31))/(8.5 xx 10^(28) xx (1.6 xx 10^(19))^(2) xx 25 xx 10^(-15))`
`=9.1/(8.5 xx (1.6)^(2) xx 25) xx 10^(-6)`
`rho = 1.6 xx 10^(-8) xx 25 xx 10^(-6)`
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