Electrons are allowed to be accelerated through a 300V potential difference.
a) Determine the electron's kinetic energy, total energy, and velocity.
b) Repeat for a proton instead of electron
c) Assume a potential difference of 1MV instead of 300V, repeat the above calculations
The Attempt at a Solution
It's been 2 years since a quantum mechanics course or physics course for that matter so bare with me if I missed something obvious.
KE is the same for both the electron and proton, 300eV
This translates to 4.8*10^-17J (from 1eV=1.6*10^-19J)
***What is the total energy?? I know it is PE+KE+U, but I can't remember how to find PE for electrons or protons. As the proton or electron is accelerated through the 300V, the KE gained=PE lost, correct? If so does that mean my total energy=2*KE or just KE?
I then used this and the mass of electron/proton to find V.
I calculated, for electron V=1.0271*10^7m/s, and for proton V=2.398*10^5m/s (from classical expression) what is the "threshold" where you must use relativistic equation? I know v<<c uses classical but what is considered much greater than c?
KE=10^6eV=1.6*10^-13J from same method as above.
Here I had to use relativistic equation for electron to find V=2.8228*10^8m/s, but used classical eq for proton and V=1.384*10^7m/s.
Is this the correct use of classical vs. relativistic equation?
If you made it to the end, thanks so much in advanced for the help!!!!