After only recently learning about Cathode ray tubes at school i was taught that the striations caused in the tubes were the result of ionisation on the particles within the tube. Though this seems most correct i have also read in text books and been told by others a couple of other reasons for striations. Such as variations in pressure(in a textbook i read but i dont think its very likely) and electrons travelling through the tubes(basically ionising but the explination was a little different). If someone would happen to know the correct reason your help would be much appreciated. Also, to do with cathode ray tubes in, particlular the rotating wheel in a tube prac, we were taught that this experiment proves the property that cathode rays carry energy AND momentum. I understand they carry energy but i am not so convinced THEY themselves carry momentum. If anyone could please clarrify. Cheers!