EE40Lecture 3Venkat AnantharamI-V Characteristic of ElementsShort Circuit and Open CircuitShort Circuit and Open CircuitExample: Power Absorbed by a ResistorTerminology: Nodes and BranchesGraph associated to a circuitCircuit Nodes and LoopsSlide 1EE40 Spring 08 Venkat AnantharamEE40Lecture 3Venkat Anantharam1/28/08Reading: Chap. 2Slide 2EE40 Spring 08 Venkat AnantharamI-V Characteristic of ElementsFind the I-V characteristic.i+_+Vab_abiRvsvSlide 3EE40 Spring 08 Venkat AnantharamShort Circuit and Open Circuit• Short circuit– R = 0 Æ no voltage difference exists – all points on the wire are at the same potential.– Current can flow, as determined by the circuit• Open circuit–R = ∞ Æ no current flows– Voltage difference can exist, as determined by the circuitSlide 4EE40 Spring 08 Venkat AnantharamShort Circuit and Open CircuitWire (“short circuit”):• R = 0 Æ no voltage difference exists (all points on the wire are at the same potential)• Current can flow, as determined by the circuitAir (“open circuit”):• R = ∞ Æ no current flows• Voltage difference can exist, as determined by the circuitSlide 5EE40 Spring 08 Venkat AnantharamExample: Power Absorbed by a Resistorp = vi = ( iR )i = i2Rp = vi = v ( v/R ) = v2/RNote that p > 0 always, for a resistor Æ a resistordissipates electric energyExample:a) Calculate the voltage vgand current ia.b) Determine the power dissipated in the 80Ω resistor.Slide 6EE40 Spring 08 Venkat AnantharamTerminology: Nodes and BranchesNode: A point where two or more circuit elements are connectedBranch:Slide 7EE40 Spring 08 Venkat AnantharamGraph associated to a circuit• First determine all the nodes in the circuit.• Draw a line diagram where every pair of nodes that is connected by a circuit element in the circuit is connected by an edge in your diagram. • This is called the graph of the circuit.Slide 8EE40 Spring 08 Venkat AnantharamCircuit Nodes and Loops•A node is a point where two or more circuit elements are connected.•A loop is formed by tracing a closed path in a circuit through selected basic circuit elements without passing through any intermediate node more than
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