Question

Find the mobility of electrons in copper if there are 9 x 1028 valence electrons/m3 and the conductivity of copper is 6 x 107 mho/m. I I​

Answer 1

Correct option is

Take a copper wire with 1cc volume. Weight = 8.96g

8.96 No. of atoms = x No = 63.5

0.8497 x 1023

No. of electrons = 0.8497 × 1023 Conductivity = 1/resistivity = nxex

m.

n = no. of electrons

e electronic charge. m = mobility of electrons.

106 1.7 = 0.8497 × 1023 × 1.6 × 10 -19

m

m = 43.25cm²/V s

C 43.25cm²/V s

Answer 2

Given: Number of electrons per unit cubic meter = 9×10²⁸ electron/m³

           Conductivity = 6 × 10⁷ mho/m

To find: Mobility of electrons

Solution:

• Mobility is the measurement of the ease with which a charged particle moves through a solid material under the influence of an electric field.

• It is defined as the value of drift velocity per unit of electric field intensity. Therefore, the faster the electron moves in an electric field, the more is the mobility of the electron.
• Its SI uni is m²/Vs

Mobility = conductivity/ electron density × charge on electron

             = 6×10⁷/9×10²⁸×1.6×10⁻¹⁸

             = 0.416 × 10⁻³ m²/Vs

Therefore, the mobility of electrons in copper will be 0.416 × 10⁻³ m²/Vs.