I just did a test yesterday and there was a question about cathode ray tubes, it went soemthing liek this. Albert calutated the charge to mass ratio of the cathode rays to be 1.3*10^11 and his velocity to be 3*10^8. His answers didnt agree to that of the text book. Marie another student, explain to Albert why his calculation were probably correct for this situation. What did Marie say? I wrote that perhaps it wasnt a perfect vacuum so particle collisions may have slowed to electrons. Also mass dilation would have slowed to electron. Is this correct? Im not sure whether the textbook calcultion already take into account mass dilation. Also my friend suggested length contration/time dilation would have effected its velocity. I wasnt quite sure becuase its not in an inertial frame of reference becuase the elctrons were accelerated to that speed. Any input will be useful. Thanks!