First encounters with Electricity
Electricity is form of energy ,but cannot actually see it , hear it or smell it .We risk the danger of electric shock if we try to touch it. The electric Bulb gives light , the radio gives sound and the electric stove cooks our food. There two forms of electricity called Static electricity ,which means that it stays in one place .The other is Current Electricity because it flows.
The word Electricity comes from the Greek word ELETRON which means amber. Amber is hard fossilized tree resin Thales, a Greek philosopher noticed that that when amber bead was rubbed with a piece of silk cloth something strange thing happened .When the amber bead was placed near small pieces of straw they jumped up to cling to the amber, he discovered a new force .The straw was attracted to the amber.
In the 16th century ,Sir William Gilbert did a scientific experiment and found that other substances like sulfur and glass could attract tiny objects just like amber. He called these substances ELECTRICS he believed that these substances were rubbed they became charged or filled with Electricity. Sir William Gilbert was the first man who gave the name Electricity.
In1733 a French scientists ,Charles du Fay hung two beads on separate cotton threads .When the beads had been charged by rubbing each one with a cloth he placed them side by side. He was surprised to see that they repelled or pushed each other apart. Two glasses beads when charged also repelled each other. But he was astonished to find that when a charged glass beads was put near a charged amber bead they attracted each other .Obviously the electric charge in the glass bead was some how different to the charge in the amber bead.
In 18th century Leyden invented an Leiden jar. This jar could actually store electricity and released it again The device is today called a Capacitor.
A famous American Benjamin Franklin were risking their lives by flying a kite during a thunder storm. Franklin had a meta door key tied near the lower end of the kite string and was able to see sparks jump between the key and his finger . This was a very dangerous experiment and some books tell of a Russian scientists who tried to do the same thing and was killed. The experiment lead to the invention of the lighting conductor which is use for protecting tall buildings from the lighting strikes
Modern synthetic fibres and plastics easily become charged with static. You have probably noticed the crackles and spark when you take off a nylon shirt or blouse in a darkened room . The spark as the charge leaks away is really a flow of current. Static and current electricity seem to have something in common.