Answer
We can rank the pairs according to the drift speed as follows:
$(top-bottom) ~\gt~ (front-back) ~\gt ~(left-right)$
Work Step by Step
We can write a general expression for the drift speed:
$v_d = \frac{J}{ne}$
$J$ is the current density
$ne$ is the carrier charge density
Note that the carrier charge density is the same in all three cases.
Therefore, the ranking for the drift speed is the same as part (b).
In part (b), we ranked the pairs according to the current density as follows:
$(top-bottom) ~\gt~ (front-back) ~\gt ~(left-right)$
We can rank the pairs according to the drift speed as follows:
$(top-bottom) ~\gt~ (front-back) ~\gt ~(left-right)$
