Concerning Electrophorus: I do not understand how touching the metal will allow you to transport negative charge when using glass as the base.

If the glass is positive then the polarization would leave positive charge on the end you touch. My understanding is that positive charge comes from protons but in a metal protons cannot move, only electrons can. What does touching the metal do that leaves the overall charge of the metal negative?

I'm adding in that he does this on lecture 5 around 29:00.

Question

Concerning Electrophorus: I do not understand how touching the metal will allow you to transport negative charge when using glass as the base.

If the glass is positive then the polarization would leave positive charge on the end you touch. My understanding is that positive charge comes from protons but in a metal protons cannot move, only electrons can. What does touching the metal do that leaves the overall charge of the metal negative?

I'm adding in that he does this on lecture 5 around 29:00.

anonymous · Answer

when the glass rubbed it is positively charged.when you keep metal plate on glass the charge is not transferred to plate as glass is not good conductor and also macroscopic contact is not good.so induction takes place in metal plate.Negative charge is formed near glass in metal as positive charge in plate.But as you know charge conservation equal amount of positive charge is formed on opposite side of metal.so when you touch the plate from above electrons from our body come in plate as our body is good conductor.these electrons from our body will cancel out positive charge on upper side of plate .after they cancel each other out , the net charge on plate is negative.|dw:1342447472303:dw||dw:1342447714413:dw|
Hope You get it.