1. The problem statement, all variables and given/known data Here is the Task: The solar wind streams off of the sun in all directions at Speeds of about 400 km/s. It contains roughly equal number of electrons and Protons. Near the earth we find in a cube with a side length of 1 m about 8.7 * 10^6 Protons. The velocity of These Protons is 470 km/s. Find the electric current produced by the flow of These Protons through a cross-sectional area of 1 m^2. 2. Relevant equations The solution should be: 6.6 * 10^(-7) 3. The attempt at a solution I really don't have an idea how to integrate the solar wind into my equation. Why is (8.7 * 10^6 * 1m^2 * (1.6 * 10^(-19)) / 470 000 m/s wrong? What has the solar wind to do with that cube? Can someone please help me and give me some tips? Thanks in advance!