Appendix b. Outstanding scientists

I. Read the texts. Outstanding Scientists

The first discoveries of electricity were made back in ancient Greece. Greek philosophers discovered that when amber is rubbed against cloth, lightweight objects will stick to it. This is the basis of static electricity.

Over the centuries, there have been many discoveries made about electricity. We’ve all heard of famous people like Benjamin Franklin and Thomas Edison, but there have been many other inventors throughout history that were each a part in the development of electricity.

Volta

S peaking of electricity in motion, reference should be made to Volta, professor of natural history, at the University of Pavia, Italy. Volta was a clever experimentalist, with a thorough knowledge of all that had been done by others in the field of electricity, a great scientist. In 1800, he constructed the first source of steady, continuous current – the voltaic pile. The voltaic pile was the first battery transforming chemical energy into electrical energy. It is to this invention that we owe the development of modern electrical science and industry.

Georg Simon Ohm

Georg Simon Ohm (16 March 1789 – 6 July 1854) was a German physicist. As a high school teacher, Ohm began his research with the recently invented electrochemical cell, invented by Italian Count Alessandro Volta. Using equipment of his own creation, Ohm determined that there is a direct proportionality between the potential differene (voltage) applied across a conductor and the resultant electric current – now known as Ohm’s law.

Using the results of his experiments, Ohm was able to define the fundamental relationship among voltage, current, and resistance, which represents the true beginning of electrical circuit analysis.

Georg Simon Ohm was born at Erlangen, Bavaria, son to Johann Wolfgang Ohm, a locksmith and Maria Elizabeth Beck, the daughter of a tailor in Erlangen. They were a Protestant family. Although his parents had not been formally educated, Ohm’s father was a respected man who had educated himself to a high level and was able to give his sons an excellent education through his own teachings. Some of Ohm’s brothers and sisters died in their childhood, only three survived. The survivors, including Georg Simon, were his younger brother Martin, who later became a well-known mathematician, and his sister Elizabeth Barbara. His mother died when he was ten.

Ohm’s law, that electric current is proportional to a potential difference, was first discovered by Henry Cavendish, but Cavendish did not publish his electrical discoveries in his lifetime and they did not become known until 1879, long after Ohm had independently made the discovery and published himself. Thus the law came to bear the name of Ohm.

James Joule

A few years after Georg Ohm made his discovery, the English physicist James Joule made his own investigation of how electrical energy works. Joule was interested in how one form of energy can be converted to another. One of the changes he studied was the conversion of electrical energy to heat.

Joule found that the amount of power in an electric circuit depends on two things: the voltage of the circuit and the amount of current flowing in it. The more current a circuit has, the more power it delivers. And the more voltage a circuit has, the more power it delivers. The power produced by a circuit can be calculated by multiplying the voltage times the amount of current:

This rule is known as Joule’s law. It tells us that increasing either the current or the voltage in a circuit increases the power that the circuit produces.