1. The problem statement, all variables and given/known data Through a fluorescent tube of a diameter of 3cm cross the transversal secion per second 2x10^18 electrons and 0.5x10^18 positive ions (with charge +e) What is the current that goes through the tube? 2. Relevant equations I=Vd*n*e*A 3. The attempt at a solution I have Vd*n for the electrons that is 2x10^18 I have Vd*n for the electrons that is 0.5x10^18 I calculate the area as 2pi(3/2)^2 And I have the charge of an electron I know that talking about current you don't have to make a distinction between positive and negative charges, but that's theroy. In practice I don't know whether to add the current generated by the positive charges with the other one, to substract them, or what? How am I supposed to proceed in this cases? Thanks in advance.