In a conductor, if the number of conduction electrons per unit volume is 8.5 × 1028 m –3 and mean free time is 25 fs (femto second), it'* approximate resistivity is : (me = 9.1 × 10–31 kg)
(1) 10–5 Ωm (2) 10–7Ωm (3) 10–8 Ωm (4) 10–6 Ωm
Correct option (3) 10–8
Explanation
