1. The problem statement, all variables and given/known data A beam contains 3.95×108 doubly charged positive ions per cubic centimeter, all of which are moving north with a speed of 1.64×105 m/s. What is the magnitude of the current density? 2. Relevant equations J = nev n = electron density e = electron charge v = drift velocity 3. The attempt at a solution J = nev J = 3.95e8 * 1.6e-19 * 2 * 1.64e5 J = 2.07e-5 A/m^2 I'm getting marked wrong for this?