The number density of free electrons in a copper conductor is \(8.5×10^{28}~\text  m^{–3}.\) How long does an electron take to drift from one end of a wire \(3.0~\text m\) long to its other end?
(the area of the cross-section of the wire is \(2.0×10^{–6}~\text m^2\) and it is carrying a current of \(3.0~\text A\))
1. \(2.7 \times10^{4}~\text s\) 
2.​​​​​​​ \(3.3 \times10^{4}~\text s\) 
3.​​​​​​​ \(2.0 \times10^{3}~\text s\) 
4.​​​​​​​ \(3.9 \times10^{3}~\text s\)