Question

A potential difference of 100 V is applied to the end of a copper wire m long .Calculate the average drift velocity of electron compare it with the thermal velocity at 27° , given conductivity of copper is 5.8×10^-8 ohm/m no. density of electron is 8.5×10^28 electron/ m3. Hint - ans. 0.43 m/ sec
Please write the complete solution .
And please write relevant answers wrong answer will be reported. ​

Answer 1

compare drift velocity and thermal velocity

Vd/Vrms=3.67×10^6

Answer 2

Average drift velocity of electrons is 0.43 m/s

Explanation:

Potential difference applied = 100V

length of wire = 1m

Therefore, electric flux = V/l = 100/1 = 100V/m

we know that current density :

J =  σE = neVd

drift velocity:

Vd =  σE/ne

= (5.8*10^7*100) / (8.5*10^28*1.6*10^(-19))

Vd = 0.43 m/sec

Thermal velocity at T = 300K

Vrms = √(3kT/m)

= √(3*1.38*10^23*300)/(9.1*10^31)

Vrms= 1.17*10^5 m/s

hence, the average drift velocity of electron is 0.43 m/sec and Thermal velocity is  1.17*10^5 m/s