1. The problem statement, all variables and given/known data A piece of n-type germanium is 2.0mm wide and 0.25 mm thick. At a certain temperature, the number of conduction electrons per cubic metre is 6 x 1020 m-3. What is the average drift speed of the electrons when a current of 1.5 mA flows? (e=1.6 x 10-19 2. Relevant equations I=nAve 3. The attempt at a solution So I converted all the units to SI base. 1.5/1000 = 6 x 1020 x (0.125/1000)2 x pi x 1.6 x 10-19 x v v = 318.309... v=318 metres per second (3sf). But the answer booklet gives 31 metres per second. Am I wrong or is it wrong? Thanks!