Past exam of the physics 2 paper of the University of Oxford / 2014 resit / 7 / b

At the largest admitted orbit, $r=R$ and $m_p{v}_{\max }=eBR$. ConsequentlyUsing $e=1.602176634\times 10^{-19}\mathrm{C}$ and $m_p\simeq 1.67262\times 10^{-27}\mathrm{kg}$ with the specified $B$ and $R$ yieldsThis is about $0.160c$; the displayed results use the nonrelativistic approximation explicitly requested by the paper. The drive amplitude controls the energy gain per gap crossing and hence the number of turns, but the ideal orbit-radius limit is set by $B$ and $R$.