In this section, we will learn about objects that manipulate the flow of electricity. They do certain tasks for us, like capacitors and transistors. To help us, we have our good old friend Spark - an electrical engineer. "Thank you for joining us again Spark."
"You're quite welcome."
"Now, can you please tell us about what capacitors and transistors do?"
"Why certainly. Picture this scene, think of a current or flow of water. Now, picture that there is a huge empty tank of water in front of the water flow. What happens? You probably have figured out that the water doesn't continue to flow forword until the tank is full, right? Well, that is exactly what a capacitor does. Essentially, a capacitor is a reservoir of electric current/charge. It fills until it is full, and as soon as it is full, it discharges, or empties. This process continues as long as there is an electric current behind the capacitor. When the current behind the capacitor stops, the capacitor discharges any stored charge. Hence, we can have power running through the circuit even if the power source has been removed - the capacitor provides this charge."
"Very storing Spark! You've told me about capacitors, but where are they used?"
"Just about everywhere. Capacitors are used in radios, television, computers, printers, etc. Because they can store charge, they serve a very useful purpose in electronics."
"What about transistors - I've heard of them a lot but I really don't know what they do? Could you tell me what they do?"
"Sure. Once again, think back to the situation of a river of water. Now, picture another river crossing the river path. For a boater on one of the rivers, he would have a tough time crossing the intersection because of all the interfering currents. A transistor regulates this current interference. Like a switch on a rail road track, a transistor allows current to flow along one path, or another."
"What about all this stuff I here about gates, and logic with transistors?"
"As I was saying, a transistor acts as a switch or a gate for electrons. Because it acts as a switch, it can either be on or off. If you think about pure logic, something can either be true or false. If you take the on or off functions of a transistor to be either true or false, the transistor can tell you, based upon which way the current is flowing if it is true or false. If you take thousands of thousands of transistors, you can get the set of transistors to make decisions, or add numbers depending on which path the current is flowing. Integrated Circuits, or IC chips are what all computer brains are made up of. For example, the Pentium processor has millions of millions of transistors to allow it to make decisions and do some work. So it is the manipulation of using a transistor over and over again millions of times that allows a computer, a calculator, and your car to work the way they do."
"That was very intriguing. But I have a question for you. How can people fit over a million transistors on such a small chip?!"
"Well, they use magic....just kidding. What they do is, they use extremely precise instruments and ultra clean environments to make chips that small. It's a real delicate and expensive process. That's why a chip so small costs so much."
"That is marvelous! I didn't mention this at the beginning, but I would really like to know what a resistor does?"
"That won't be a problem. Think back to the situation of the water river. Now, picture what happens to water when you place a dam in front of the flow of water, and let only a little bit of water through the dam. That's what a resistor does. Like its name implies, a resistor reduces the flow of charge. I know you must be asking yourself why would anyone want to reduce the flow of charge? Well some electronic components are very delicate and can only have a little bit of charge flow through them. So a resistor reduces the current for the components. If you think back to the picture of a dam, the resistor also increases the pressure or voltage in a circuit. Once again, some electronic components require more voltage, so a resistor helps to solve the problem."
"Thank you so very much for that information Spark. It was an 'electrifying' experience!"
"You're welcome. Hey, you know, people have been telling me about your hideous hat, but I think it really is quite neat - very mystical. You should go on Sesame Street!"
"Ha ha, thank you - that's a first."
This section has taught us about the three basic components of a circuit: a capacitor, transistor, and a resistor. You can learn more by following the suggested links, and or by following our electric adventure, and learn about magnetism. So click below to learn more!
Electricity flows like water
A transistor is like a switch
A capacitor is like a resevoir
A resistor is like a dam with a hole