What is speed on this ion?

Question

An ion (charge = -e) enters a mass spectrometer.

The speed of the ion is 2.50×106 m/s; the magnetic field is B = 2.06 T; the diameter of the circular path is 0.379 m. Determine the mass of the ion

Answer 1

As I told you in your other homework problem, the cyclotron frequency formula is:

f = (B * q ) / (2 * pi * m)

It helps to know that after one period T, v*T must be one circumference: v T = 2 * pi * r.

That means that f = v / (2 pi r), and therefore that:

v = B * q * r / m.

Or that:

m = B q r / v.

Plug and chug.