# Assume that in the 70 million electron volt (MeV) betatron, the radius of the stable electron orbit is 28 cm. Calculate the frequency of the applied electric field. I have the angular velocity of the electron (w) = 1.07 x 10^9 I assumed that the frequency of the electron= frequency of applied electric field From that I found the frequency(f) of the electron as, w = 2(pi)f f = 1.7 x 10^8 Hz But the answer given in my book is 1.7 x 10^6 Hz. Is it a typographic error?
I imagine that a 70 Mev electron is travelling relativistically. Working with your radius and w I come up with 0.95 c or there abouts. That won't be correct of course. You're going to need to use SRT to convert 70 Mev into the the V of the electron, also the "relativistic mass" in the charge to mass ratio. (I know, we're not supposed to use relativistic mass, we're supposed to use the term "relativistice transverse inertia" or something like that now.) >>edit If the radius of 28cm is a given of the problem, then all you will need is to use SRT to figure the V of a 70 Mev electron. Forget the rest.
