Answer
$t = 4.0~minutes$
Work Step by Step
We can find the drift speed:
$J = (ne)~v_d$
$\frac{i}{A} = (ne)~v_d$
$\frac{i}{\pi~r^2} = (ne)~v_d$
$v_d = \frac{i}{ne~\pi~r^2}$
$v_d = \frac{12~A}{(8.49\times 10^{28}~m^{-3})(1.6\times 10^{-19}~C)~(\pi)~(2.6\times 10^{-3}~m)^2}$
$v_d = 4.16\times 10^{-5}~m/s$
We can find the time it takes to move 1.0 cm:
$t = \frac{distance}{speed}$
$t = \frac{1.0\times 10^{-2}~m}{4.16\times 10^{-5}~m/s}$
$t = 240~s$
$t = 4.0~minutes$
