I find it hard to believe that you were asked to calculate current and you were not taught current definition.
Investigate the book if you like. Chemistry: Principles & Practice 2e, Chapter 7. There's no mention of currents; I couldn't find it in the index either. That's why I'm thinking it's solvable using that KE equation, or some variant of it.
For example, does this make sense:
Part 1
Multiply the charge with the # of electrons and convert the product to microamperes.
Part 2
Use KE = hv, with KE = to answer from part 1.
Solve for frequency. Use E = hv to solve for Energy. Multiply by 6.022e23 to find # of protons needed to be absorbed.