Suppose in an electron gun, electrons are emitted from a filament and are accelerated by an electric field to an opening, as shown. The charge on an electron is (-e), where e = 1.6 * 10^-19 C.
(a) If the voltage (same as electric potential) at f is 140 Volts, what is the potential energy of an electron at f?
(b) The electrons come off the filament with very low velocity, hence with very little kinetic energy. So, what is the total energy of an electron at f?
After the electrons exit the gun at = 0 voltage. Thus, what is the potential energy of an electron at 0?
(d) Given that the mass of an electron is m = 9.1 * 10^-31 kg, how fast must an electron be going when it exits the gun?
When an electron moves subject only to a magnetic force, its kinetic energy does not change. State the work-energy theorem (see text) and then explain why the magnetic force does not change the electron's kinetic energy, and hence the speed remains constant.
A beam of electrons makes a circular orbit in the plane perpendicular to an applied magnetic field. If the electron speed is 15 mega meters per second, how strong must the field be if the radius of the circle is 12 cm? Show your work, starting with uniform circular motion.