(a) The magnetic force experienced by a charged particle is:
where
q is the charge
v is the velocity of the particle
B is the magnitude of the magnetic field
is the angle between the directions of v and B
The proton in our problem has a charge of
, and it travels through a magnetic field with strength
The direction between its velocity and B is
, and the force exerted on the proton is
. Re-arranging the previous equation and using these data, we can find the value of v:
(b) Using the mass of the proton,
, we find its kinetic energy:
And keeping in mind that
, we can convert this value into electronvolts: