It is usually said that the branch of science called electronics began with the invention of the vacuum tube. Tubes improved over the years but soon there were no improvements that could be made to them. The transistor age began in the mid nineteen fifties. One of the most advantageous things about a transistor is that it can take a tiny signal that cannot be heard and amplify it so that it fills a room with sound. A transistor can also work as a switch at very high speeds. Another difference between the vacuum tube and the transistor is that a tube works in a vacuum. A transistor works in solid material hence the term solid state is used to describe transistorized devices.37
Transistors also turn on instantly. Vacuum tubes need time to warm-up. Vacuum tubes are also more delicate. If dropped they probably will not function. Not so with a transistor. They are rugged a can operate for years. Transistors have continued to be shrunk and there seems to be no stopping them. Without the transistors inside the small chips now being produced there would have been no miniaturization of phones, calculators, computers television, or radios. Without the ability to shrink the computers necessary for a space capsule to function the American space program would surely have been indefinitely grounded. Vladimir Zworykin and John Baird worked during the 1920s on the concept of television. However it was not until the forties and fifties that television came into its own. In 1947 William Shockley, John Bardeen, and Walter H. Brattain invented the transistor. In 1955 William C. Pfann found a way to remove impurities from semiconductors.38
What has been presented is a very brief and simplified version of the history of electronics and magnetism. Not being a scientist I have tried to choose events that seemed to convey simple but important discoveries that I could make understandable to my students and that kept a certain historical pattern going. I'm sure that it would be obvious that to the trained person that I have simplified as much as possible due to my own limitations and those of my students. I believe that the combination of facts with hand-on experience will make the unit successful.
The unit would end with the presentation of final projects or models. Students would hopefully see the growth of knowledge that has taken place over hundreds of years.