Phys 202 1st Edition Lecture 10Outline of Last Lecture I. Circuits with multiple resistors and/or multiple capacitorsOutline of Current Lecture II. Kirchhoff’s RulesIII. Current ConservedIV. Loop RuleCurrent LectureKirchhoff’s Rules:Kirchhoff’s rules describe several equalities dealing with current and voltage through a circuit. Current is conserved:Kirchhoff’s first law, which is also sometimes called the “node rule”, states that at any node or point in anelectrical circuit, the sum of currents flowing into that node is equal to the sum of currents flowing out of that node. Essentially, this means that the current coming in to a system must be equal to the current coming out of the systemSo, for the figure above, I1+I2+I3=I4+I5Example:If you apply the node rule at node A: I1+I2=I3If you apply the node rule at node B: I3=I4+I5These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute. I1I2I3I4I5I1 R1 D A I2I3 R4 E1 E3 R2 C I5 B I4 E2 R3Loop Rule: Kirchhoff’s second rule is called the voltage rule, or sometimes the loop rule. This rule states thatthe sumof the potential differences (V) around any closed loop is equal to zero. In the figure above, you can follow the path of nodes around the circuit from A to B to C to D and back to A. In this case, the sum of all the potential differences around the loop should be equal to zero. Remember that the potential difference is equal to the current times the resistance (IR). In the case of the figure above:-i3R2 – E1- I5R3-E2+ E3-I5R4-I1R1=0When you travel through a voltage source in the circuit, pay attention to the positive and negative leads. If you move across the battery from a positive lead to a negative lead, you are moving down in potential. If you move from a negative lead to a positive lead, you are moving up in potential. If you are going up in potential (from an area of lower potential to an area of higher potential), then VE is positive. If you are going down in potential (from an area higher potential to an area of lower potential), then VE is
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