Kinetic Energy's Effect on Electron's Radius in Magnetic Field

mirandab17

An electron moves in a circular orbit of radius r in a magnetic field. The electron moves in a path perpendicular to the magnetic field. If the kinetic energy of the electron is doubled, what is the new radius of its path?

What formula would I use to go about this? Is this about mass spectrum? So I would go about using Fnet=ma, and then Fb (of a single charge) = mv^2/r.
So Bvq = mv^2/r... then where?

Please help! Test tomorrow! :(

Steely Dan

Sure, you're on the right track. Use that to solve for [itex]r[/itex] first. Then think about which quantity in the equation for the radius will change if the kinetic energy is doubled, and figure out how much it will be changed by.