Elecricity Definition and 102 Threads

Can someone please check my answers here, there are loads of formulaes been give that I haven't used so I'm not sure if they are right or not, thanks.

A conducter with two diameters d1 and d2 (one single piece), carries a current.having lengths L. What is same n=free electrons in one cubic mtr e=constant electronic charge=1.6X10^-19columbs Vd=drift velocity I solved as Let total electrons in rod A be N therefore I=N*e*Vd*A/A*L...