Resistors - Resistors There is always some resistance in...

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Resistors There is always some resistance in every circuit. A circuit is always made up of some wire, so there will be some resistance there. Even the battery has parts that offer resistance to the flow of electrons. The only circuits that come near to zero resistance are superconductors. This resistance that is from the parts of the circuit itself (especially the battery) is called internal resistance . This internal resistance is usually drawn into a circuit diagram ( schematic ) as shown in Figure 1. Notice the squiggly line just before the positive terminal of the battery? That’s to show the internal resistance of the circuit. That symbol, drawn any other place in the circuit, represents an actual resistor placed in the circuit. A resistor is a device found in circuits that has a certain amount of resistance. Why would you ever want to add resistance to a circuit by using a resistor? The most common reason is that we need to be able to adjust the current flowing through a particular part of the circuit. If voltage is constant, then we can change the resistor to change the current. I = V R If “V” is constant and we change “R”, “I” will be different. Actual Resistors The resistors that you would most likely see if you opened up a CD player, VCR, or other electronic device would look like the ones in Figure 2. They basically look like little cylinders with colored lines painted on
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Resistors - Resistors There is always some resistance in...

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