An experimentalist rubs an acrylic rod with a dry silk cloth, causing the rod to acquire a positive electrostatic charge.
Explain, in terms of moving charges, how the acrylic rod becomes positively charged.
The charged acrylic rod is brought close to, but does not touch, a lightweight, neutral metallised sphere suspended from a thin nylon thread. The sphere is observed to swing towards the rod. Explain why this attraction occurs.
Suggest why the electrostatic charge remains localized on the acrylic rod even though the experimentalist is holding it by its other end with their bare hand.
Suggest why this demonstration is much less successful when conducted in a room with highly humid air.
