Question

In lecture 4, WL demonstrates the tendency of electrons to move from lower potential to higher ones with a fluorescent due to potential differences created by the electric field. The fluorescent did not need to touch the Van de Graaff, but in earlier sessions we had to touch some staff in order to get charged. What is here the difference? Let me put the question in another way: Why does WL have to touch the fluorescent whereas the fluorescent does not have to touch the Van de Graaff???

Answer 1

I Think when WL touches the side of the tube he is acting like ground and that's why one side of the fluorescent tube becomes V=0. The other will have the potential given by the Van der Graff Generator.

I think that's why when he touches it, it becomes brighter.