1. The problem statement, all variables and given/known data Assume a steady stream of α particles travels with a constant energy of 20 MeV and carries a current of 2.5 μA. a) If the beam is directed perpendicular to a plane target, how many α's will strike this target in 8 seconds? b) At any given instant, how many α's are in a 20 cm length of the beam? c) Through what electrical potential diffence is it necessary to accelerate each α from rest to bring it to the energy of 20 MeV? 2. Relevant equations ? 3. The attempt at a solution I have absolutely no idea how to solve any of these questions. The only thing I could think to do was find how many protons were in the current by multiplying 2.5E-6 by 8 seconds to give me the amount of Coulombs. I then multiplied that by 6.2415E18 e/C to get the number of elementary charges. I thought this solution may be the answer to part a) but it wasn't. So now I'm lost. Any help will be greatly appreciated.