Chapter 28, Problem 9P

A proton (charge + e, mass m_p), a deuteron (charge + e, mass 2m_p), and an alpha particle (charge +2e, mass 4m_p) are accelerated from rest through a common potential difference ΔV. Each of the particles enters a uniform magnetic field $\stackrel{\to }{B}$, with its velocity in a direction perpendicular to $\stackrel{\to }{B}$. The proton moves in a circular path of radius r_p. In terms of r_p, determine (a) the radius r_d of the circular orbit for the deuteron and (b) the radius r_a for the alpha particle.