Find the potential difference av, required to stop an electron (called a 'stopping potential) moving with an initial speed of 1.89 x 10' m/s. (b) would a proton traveling at the same speed require a greater or less magnitude potential difference? explain this answer has not been graded yet (c) find a symbolic expression for the ratio of the proton stopping potential and the electron stopping potential, av, jav, the answer should be in terms of the proton mass m, and electron mass me

Cyclotrons are widely used in nuclear medicine for producing short-lived radioactive isotopes. these cyclotrons typically accelerate h- (the hydride ion, which has one proton and two electrons) to an energy of 5 mev to 20 mev. this ion has a mass very close to that of a proton because the electron mass is negligible—about 1 2000 of the proton’s mass. a typical magnetic field in such cyclotrons is 1.9 t. (a) what is the speed of a 5.0-mev h-? (b) if the h- has energy 5.0 mev and b = 1.9 t, what is the radius of this ion’s circular orbit?