An electroscope is a device that detects charge on objects that touch it or are brought near it. John rubs a piece of cotton fabric on a plastic rod and then touches the rod to the electroscope. What methods of charging does John use?

John charges the rod through induction, then charges the electroscope through friction.
John charges the rod through conduction, then charges the electroscope through induction.
John charges the rod through friction, then charges the electroscope through induction.
John charges the rod through friction, then charges the electroscope through conduction.
D

on passing the small ampere of electric current through the tube made of ar and hg of cfl generates uv rays which excites the fluorescent and thus emits the high radiation by consumption of just 5- 12 w in comparison to incandescent light which requires more power such as around 40 - 55 w to lighten.

moreover the life span of fluorescent or cfl is around 8000 h whereas the life span of incandescent is around 1200 h

hence, the building installed with incandescent lights bears more electricity bill.

alchemy hadn't scientific methods of study, appeal to mysticism and fantasy, the knowledge of chemistry and physics were modest at that time.

alchemy was - but as new rules were discovered it either changed into chemistry or it became "unscientific".