Question

(a) In tin at room temperature, the mobility of mobile electrons is about 1.5 ✕ 10-3 (m/s)/(V/m), and there are about 3.7 ✕ 1028 mobile electrons per m3. Calculate the conductivity σ. In actual practice, it is usually easier to measure the conductivity σ and deduce the mobility u from this measurement.

Answer 1

Answer:

The value is $\sigma = 8.88*10^{6} \ C\cdot m^2 / V \cdot s$

Explanation:

From the question we are told that

   The mobility of electron in a tiny room is  $\mu = 1.5 *10^{-3} \ (m/s)/(V/m)$

  The number of mobile electron per $m^3$ is  $N = 3.7 *10^{28}$

  Generally the conductivity is mathematically represented as

        $\sigma = N * e * \mu$

Here  $e$ is the charge on a single electron and that value is  

       $e = 1.60 *10^{-19 } \ C$

So

          $\sigma = N * e * \mu$

=>       $\sigma = 3.7 *10^{28 } * 1.60 *10^{-19} * 1.5 *10^{-3}$

=>     $\sigma = 8.88*10^{6} \ C\cdot m^2 / V \cdot s$