1. Aug 19, 2011

rob60

1. The problem statement, all variables and given/known data
90% of the cosmic rays that fall on Earth are protons. So the outside of the earth is hit by a net positive charge but does not seem to be, in particular, positively charged. How do you explain this?
One last thing: I read that a body that is exposed to radiation becomes radioactive radiation source in turn ..... I think it is generally false unless the body is contaminated with radioactive material. It is correct?
thank you

2. Relevant equations

3. The attempt at a solution
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Aug 19, 2011

daveb

In general, you are correct. Material exposed to a neutron or proton flux can become activated, which usually makes some part of it radioactive, and energetic enough electron or gamma fluxes can also do it (but it in general takes a lot of energy).