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Unformatted text preview: LAB # 31 Ohms Law The fundamental relationship among the three important electrical quantities current , voltage , and resistance was discovered by Georg Simon Ohm. The relationship and the unit of electrical resistance were both named for him to commemorate this contribution to physics. One statement of Ohms law is that the current through a resistor is proportional to the voltage across the resistor. You will test the correctness of this law in several different circuits using a Current & Voltage Probe System and a computer. These electrical quantities can be difficult to understand, because they cannot be observed directly. To clarify these terms, some people make the comparison between electrical circuits and water flowing in pipes. Here is a chart of the three electrical units we will study in this experiment. Electrical Quantity Description Units Water Analogy Voltage or Potential Difference A measure of the Energy difference per unit charge between two points in a circuit. Volts (V) Water Pressure Current A measure of the flow of charge in a circuit. Amperes (A) Amount of water flowing Resistance A measure of how difficult it is for current to flow in a circuit. Ohms ( ) A measure of how difficult it is for water to flow in a pipe. Figure 1 OBJECTIVES Determine the mathematical relationship between current, potential difference, and resistance in a simple circuit. Compare the potential vs. current behavior of a resistor to that of a light bulb. APPARATUS Power Macintosh wires Universal Lab Interface Logger Pro Current & Voltage Probe System Adjustable 5volt DC power supply...
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 Fall '08
 RABE
 Physics, Current, Resistance

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