How Many Revolutions Does a Proton Make in a Cyclotron?

[MyNewPony]

Homework Statement

A 66.0-cm-diameter cyclotron uses a 530 V oscillating potential difference between the dees.

How many revolutions does the proton make before leaving the cyclotron?

Homework Equations

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

The Attempt at a Solution

I find the cyclotron frequency:

f = ((1.6x10^-19)(0.69))/(2*pi*(1.67x10^-27)) = 1.1x10^7 rev/sec

I don't know where to go from there. How do I find the time it takes for the proton to leave the cyclotron?

 

[kuruman]

The proton will exit when it is at the radius of the cyclotron.
Can you find the proton's speed at that radius?
Can you find the proton's kinetic energy when it exits?
For every revolution, 2*530 eV are added to the proton's energy.
Put it together assuming that the proton starts with negligibly small kinetic energy. (Don't forget to convert eV to Joules).