An alpha particle (α) is accelerated in a cyclotron consisting of two D-shaped regions separated by a small gap. A constant magnetic field acts perpendicularly to the plane of the 'Dees', while an alternating electric field in the gap provides the acceleration. 
Explain why the magnetic field cannot change the kinetic energy of the alpha particle while it is inside a D-shaped region.
Show that the time interval Δt for the alpha particle to complete one semi-circular path in a Dee is independent of its speed.
The cyclotron is used to accelerate alpha particles to a maximum trajectory radius of 0.62 m. The magnetic flux density is 0.38 T. Calculate the maximum velocity of an alpha particle as it exits the device. Take the mass of an alpha particle as 6.64×10−276.64 \times 10^{-27}6.64×10−27 kg and its charge as 3.20×10−193.20 \times 10^{-19}3.20×10−19 C.