resistors_ohmslaw

# resistors_ohmslaw - Resistors and Ohms Law A wire is an...

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1 Resistors and Ohms Law A wire is an ideal conductor with no resistance (at least for our discussion). In contrast, a resistor is a component that purposefully impedes or opposes the ﬂow of electrons. As an externlly applied electric ﬁeld is applied to force current through a resistor, the electrons diffuse through the resistive material like a gas through a sponge. The electrons gain energy from the external ﬁeld but once they start to move, they bump into a atom in the resistive material and loose some kinetic energy. How fast the electrons bump through the resistor depends on the intensity of the externally applied ﬁeld. The stonger the ﬁeld, the faster the electrons diffuse through the material increasing the num- ber of electrons passing through per second. The speed at which electrons diffuse through the mate- rial is called the drift velocity and it is proportional to the applied voltage. A water analogy: If current ﬂow is water,. ...... then wires are ﬁre hoses,. ...... and resistors are drinking straws. To force more water through a drinking straw in a given amount of time, more pressure is required. Expressed as a water analogy: Electrically speaking: The expression V = I * R is commonly known as Ohms law . It describes the relationship between voltage, current and resistance. It is the most fundamental formula in electrical engineering. This

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## This note was uploaded on 04/17/2010 for the course ECE 112 taught by Professor Traylor during the Winter '09 term at Oregon State.

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resistors_ohmslaw - Resistors and Ohms Law A wire is an...

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