Earthing, done with a comb and a tap
ObjectiveTo show that a charged object loses its charge when it is given a path to the ground, which is the idea behind earthing.
MaterialsA plastic comb, small pieces of thin paper, a metal water tap or any metal pipe that runs into the ground, and a wooden or plastic object for comparison.
MethodRub the comb in dry hair and check that it picks up the paper. Now touch the comb firmly against a metal tap for two seconds, and immediately test it on the paper again. Record what happens. Then recharge the comb, touch it against a wooden door or a plastic chair instead, and test it on the paper once more.
DiscussionWhere did the charge go when the comb touched the tap? Why did touching wood not have the same effect? And how does this explain the wire that joins a fuel tanker to the ground?