Constuction
Cut the stiff sheet of paper in a manner to fit the mouth of the bottle.Make a small hole in the stiff sheet and pass the copper wire through it such that there is no gap between the wire and the paper.Remove 2 cm of insulation from either end of the wire.Bend the lower end of the wire to form a hook. Cut 2 thin alluminium strips and hang them from the hook.Place the stiff paper carefully on the mouth of the bottle and seal it with a tape.Ensure that the strips of alluminium are intact when placed in the bottle.Electroscope is ready for use.
Working
When a negatively charged object is brought closer to electroscope it repels the electrons on the surface of the electroscope.The surface of the electroscope thus becomes positively charged.The electrons repelled from the surfacemove through the copper wire and move to the alluminium strips.Thus both the alluminium strips become negatively charged .As similar charges repel therefore the 2 strips move apart.Similarly when a positively charged object is brought closer to the electroscope, it will attract electrons from the electroscope.Thus electrons move from the alluminium foil towards the surface of the electroscope. The 2 alluminium strips thus get positively charged and again repel each other.Thus whenever a charged object is brought near to electroscope there is a repulsive movement between the alluminium strips.....
