Multiple exposure photography is used to illustrate the movement of a pole vaulter. (Corbis-Bettmann)

Electrical and electronic devices and machines have become an integral part of contemporary life, ranging from household appliances and computers to huge industrial machines. When home and business owners pay the monthly bill from the electrical power company for the use of all of these items, they are paying for energy very conveniently delivered over electrical wires from the power company.

Although the delivery of electricity to homes and businesses has been possible only during the past century, static electricity was observed by the ancient Greeks over 2,000 years ago. They also noticed natural magnets, called lodestones, found near the town of Magnesia. These were important discoveries because scientists now know that electricity and magnetism are intimately related. Magnetism is used by power companies to produce the electricity used every day.

Electric Charges and Electric Force