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Unformatted text preview: LAB # 31 OHM’S LAW Introduction: 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 Ohm’s 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. Learn to identify a resistor from its color bands. Compare the potential vs. current behavior of a resistor to that of a light bulb....
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