 This is a fluorescent bulb and a tesla coil the tesla coil builds up electrons on its tip Which creates a large voltage difference between it and whatever it's near When the tesla coil is close enough to the bulb electrons begin jumping to the bulb and flying into it When inside the electrons Collide with the fluorescent wall of the bulb and create the light we see This is a cathode ray tube in it electrons flow from the cathode at the tip through a slit in this metal part and Onto the screen which is coated with zinc sulfide This is so we can see the electron beam as Zinc sulfide fluoresces in the presence of the electrons the cathode Tube has been important in discovering properties of the electron As you can see when this magnet Is placed near the tube The ray of electrons bends This is because the electrons have a charge that we know to be negative Also when the field is reversed We can see that the electrons bend in the opposite direction JJ Thompson used a CRT along with electromagnetic theory to calculate the charge to mass ratio of the electron This was a very useful value to know when our American later found charge of an electron from these two values