Franklin and his experiment
The famous story about Franklin is his kite experiment." He and his son took a kite made of silk£Øbecause it is stronger than paper£©£¬ and added a long wire to the top and a piece of silk to the end of the string with which he controlled the kite. A metal key was hung where the silk and string met. They flew the kite up into a thunderstorm£¬ keeping themselves dry under a roof. When the kite reached the storm clouds£¬Franklin noticed that all the loose parts of his string began to stand up and shake.When the kite touched lightning£¬a spark ran down the string to the key£»a rush of electric sparks began to appear on the key. As the string became wetter£¬the sparks came faster.They were sparks of electricity .Lightning was indeed electricity."(see ref 1.) It is a very dangerous experiment. The idea of the experiment was not just to explain a physical appearance, but also to help people to overcome fear from nature.
Quiz
If we change the definition of positive charge and negative charge is there any difference in Physics?
Answer
NO!
Reference
1.http://cache.baidu.com/c?m=9f65cb4a8c8507ed4fece76310428a265e0b97634b95904268d4e517c3370a1f0036f4bb50734d5bce84263a44e9141eb1a12172405061f5d1df893e89e6d26f70d37123716a874613c419ab8d1b679a71cb0cfeae6fe7bdfa3993abc5d3db010edd527326d7bacd4e45498a39ff0341e9b1e938022e12ad9d41728f2d6058ef3431b5508fe4256e769686d84b3bc63da46006e1d9&p=9d36c64ad38102ff57ea92224b00&user=baidu
2.http://en.wikipedia.org/wiki/Electric_charge