The problem is to determine whether or not relativistic effects are relevant for an electron accelerated to an energy of a) 100MeV and b) 100GeV. So I need to find the gamma factor of the electron in each of these cases.

I have used [tex]E = \gamma m_0 c^2 [/tex] and solved for gamma = 195 in the first case and 195360 in the second case, which are definitely relativistic results.

However I'm not sure I'm using the right formula here. If someone could confirm this that would be great.