Answer
(a) $J = 6.25\times 10^5~A/m^2$
(b) $v = 6.5\times 10^{-5}~m/s$
Work Step by Step
(a) We can find the current density:
$J = \frac{I}{A}$
$J = \frac{2.5~A}{(2.0\times 10^{-3}~m)(2.0\times 10^{-3}~m)}$
$J = 6.25\times 10^5~A/m^2$
(b) We can find the drift speed:
$I = v~A~n~e$
$v = \frac{I}{A~n~e}$
$v = \frac{2.5~A}{(2.0\times 10^{-3}~m)(2.0\times 10^{-3}~m)(6.0\times 10^{28}~m^{-3})(1.6\times 10^{-19}~C)}$
$v = 6.5\times 10^{-5}~m/s$
