ELECTRONICs Improvements in how they are manufactured have made the chips more readily available Modern electronic devices are almost everywhere we look Consumers started out using electronics in their phonographs but now the field has expanded to satel lite radios MP3 players and even tablet computers that use a touch screen for a key board Of course electronics are not only for home use Medicine is just one field that takes advantage of electronics all the time Doctors can get a more detailed look at the human body by using diagnostic instruments such as computed tomography CT and nuclear magnetic resonance NMR scan ners Transportation whether by road air or spaceſ also relies heavily on electronics Experiments in the late 19th and early 20th centuries by several inventors had dramatic effects Thomas Edison's 1883 dis covery of thermionic emission discharge of electrons from heated materials eventually resulted in the radio tube A few years later in 1887 Heinrich Hertz stumbled upon the pho toelectric effect in which charged particles are released from a material when it absorbs radiant energy a discovery that led to pho toelectric cells In 1904 John A Fleming 10 MILE 8
INTRODUCTION invented the Fleming valve now known as a diode The triode an electron tube consist ing of three electrodes would come about in 1906 when Lee De Forest adapted the diode I The vacuum tube led to the development of radio television and electronic computers There 1s no denying our reliance on elec tronics from the lights that illuminate our houses to complex computers that direct space probes as they hurtle through space Could more highly developed electronics come about This overview of electronics shows that there are no limits to how they can progress and change our lives Umm Umm Am I Am TTI HUI
CHAPTER 1 THE REVOLUTIONARY FIELD OF ELECTRONICS N elevision stereophonic recording and playback the computer robots and space probes are all products of elec tronics Electronics is the branch of physics concerned with the generation and behavior of electrons as in transistors and electron tubes It is especially concerned with their use in electronic devices in which electricity is used to control communicate and process infor mation These devices have caused greater changes in everyday life than those of any other technology introduced in the 20th century THE ELECTRONIC SIGNAL The basis of electronics is the electronic signal an electric current that represents information There are two basic types of electrical signals analog and digital In analog signals some continuously variable aspect of IO
THE REVOLUTIONARY FIELD OF ELECTRONICs the electrical current represents the infor mation In amplitude modulated AM radio transmissions for example the amplitude or strength of the electromagnetic radio wave is proportional to the amplitude of the signal the volume of the sound that the radio wave carries The greater the ampli tude of the radio wave the louder the sound that radiates from the radio speaker In contrast digital signals use standard ized pulses to represent numbers With a digital audio signal the amplitude of the 271 The iPad2 is a touch screen device that is smaller than a laptop com puter but larger than a smartphone Justin Sullivan Getty Images ITTHL II TTI HUI
