An electron accelerated from rest through an electrostatic potential difference of 750 kV would have a total energy of approximately
A)1.26 MeV
B)0.750 MeV
C)0.511 MeV
D)0.239 MeV
E)0.038 MeV

Question

Quizplus · Accepted Answer

The total energy of an electron accelerated through a potential difference V is given by the equation E = eV, where e is the charge of the electron (approximately 1.6 x 10^-19 coulombs) and V is the potential difference in volts. When the potential difference is given in kilovolts (kV), and we want the energy in mega-electronvolts (MeV), we can use the fact that 1eV = 1.6 x 10^-19 joules and 1MeV = 1.6 x 10^-13 joules. Thus, accelerating an electron through 750 kV gives it an energy of 750 keV, which is equivalent to 0.750 MeV. However, this is the kinetic energy. The total energy also includes the rest mass energy of the electron, which is 0.511 MeV. Therefore, the total energy is 0.750 MeV (kinetic) + 0.511 MeV (rest mass) = 1.261 MeV, which is approximately 1.26 MeV.

An Electron Accelerated from Rest Through an Electrostatic Potential Difference