Question

Using theory of drief velocity express ohm's law

Answer 1

When a potential difference V is applied across a conductor of length l , drift velocity in terms of V is given by vd= eVt /ml

If the area of cross section =A, and number of electrons per unit volume is n , then

Current I= enAvd

V/I = ml /ne2tA

Now, at a fixed temperature the quantities m,l,n,e,t A have constant values for a given conductor-

So, V/I = constant , R

R=ml /ne2tA

here, R is resistance, t is relaxation time, E is electric field , e= charge on an electron and m= mass of an electron.