in second case-

2)since the same route can be taken .therefore,total no. of outcomes will be-

5*5=25

in first case-

i)5*4=20 routes are taken,because it cant return from the same path.

it's simple............

current through any conductor is =Avne

now,number of free electrons per unit length=1*A*n

and, momentum of each free electron is=mv.

 

therefore momentum per unit length=Anmv=(I/e)m=I/s        (since.........e/m=s)

 

threfore required answer is I/s as indicated by you.

 

if i am right then rate me.

how does charge density depends on state of rest or motion?