Understanding Voltage and Current Divider Circuits in Electrical Engineering
This lecture from Rowan University's Electrical and Computer Engineering Department covers crucial concepts in electrical circuit analysis, including voltage and current divider circuits, Kirchoff's Laws, and series/parallel resistive circuits. Key learning objectives focus on defining voltage/current dividers, analyzing DC circuit configurations, and employing techniques for circuit reduction. Students gain insights into problem-solving methods that involve Kirchhoff's Current and Voltage Laws, providing a solid foundation for understanding complex electrical systems.
Understanding Voltage and Current Divider Circuits in Electrical Engineering
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Presentation Transcript
CHAPTER 3 NETWORKS 1: 0909201-01 23 September 2002 – Lecture 3a ROWAN UNIVERSITY College of Engineering Professor Peter Mark Jansson, PP PE DEPARTMENT OF ELECTRICAL & COMPUTER ENGINEERING Autumn Semester 2002
networks I • Announcements – • Homework 2 answers posted today • Returned after test Tuesday • First Test Tomorrow Ch. 3: 24 Sep • Lab 1 assignment is due • Sec 1: TODAY - 23 Sep • Sec 2: TOMORROW - 24 Sep
networks I • Today’s Learning Objectives – • Define voltage/current divider circuits • Analyze series V-sources • Analyze parallel current sources • Reduce resistive circuits • Analyze DC circuits with passive and active elements including: resistance and power sources
chapter 3 - overview • electric circuit applications - DONE • define: node, closed path, loop - DONE • Kirchoff’s Current Law - DONE • Kirchoff’s Voltage Law - DONE • a voltage divider circuit • parallel resistors and current division • series V-sources / parallel I-sources • resistive circuit analysis reduction
R1=10 _ + + V= 5v + LOOP 1 _ _ R2= 20 Start +V - vR1 - vR2 = 0 iV = iR1 = iR2 = i +V = iR1 + iR2 V = i(R1 + R2) KVL i = V/(R1 + R2) vR! = iR1 = VR1 /(R1 + R2) vR2 = iR2 = VR2/(R1 + R2)
R1=10 _ + + V= 5v + LOOP 1 _ _ R2= 20 Start +V - vR1 - vR2 = 0 iV = iR1 = iR2 = i +V = iR1 + iR2 V = i(R1 + R2) SERIES RESISTORS NOTE i = V/(R1 + R2) vR! = iR1 = VR1 /(R1 + R2) vR2 = iR2 = VR2/(R1 + R2) VOLTAGE DIVIDER
R = 2 R = 3 R = 9 R = 4 SERIES RESISTORS • resistors attached in a “string” can be added together to get an equivalent resistance.
R1=10 i1 _ + v1=50v + + I I=5A v2=20v R3= 5 i2 i3 R2= 20 v3=20v _ _ Node 1 Node 2 Node 3 Node 1 +I - i1 = 0 Node 2 +i1 - i2 - i3 = 0 Node 3 +i2 + i3 - I = 0 i2 = v2/R2 i3 = v3/R3 Use KCL and Ohm’s Law CURRENT DIVIDER
series voltage sources • when connected in series, a group of voltage sources can be treated as one voltage source whose equivalent voltage = all source voltages • unequal voltage sources are not to be connected in parallel
parallel current sources • when connected in parallel, a group of current sources can be treated as one current source whose equivalent current = all source currents • unequal current sources are not to be connected in series
loop2 loop1 PROBLEM SOLVING METHOD va vb _ _ node3 node1 node2 + + Rb Ra ib ia + ivs + vc + ic vis vs Rc is _ _ _ node4
steps taken • Apply P.S.C. to passive elements. • Show current direction at voltages sources. • Show voltage direction at current sources. • Name nodes and loops. • Name elements and sources. • Name currents and voltages.
va vb _ _ node3 node1 node2 + + Rb Ra ib ia + ivs + vc + ic vis vs Rc is _ loop2 loop1 _ _ node4 WRITE THE KCL EQUATIONS node1: node3: node2: node4:
va vb _ _ node3 node1 node2 + + Rb Ra ib ia + ivs + vc + ic vis vs Rc is _ loop2 loop1 _ _ node4 WRITE THE KVL EQUATIONS loop1: loop2:
va vb _ _ node3 node1 node2 + + Rb Ra ib ia + ivs + vc + ic vis vs Rc is _ loop2 loop1 _ _ node4 WRITE SUPPLEMENTARYEQUATIONS
10 30 45 iT i1 + 15 90 50 _ 5v 5 100 CIRCUIT REDUCTION
10 30 45 iT i1 + 15 90 50 _ 5v 5 100 • Begin with loop on far right. • Combine the three resistors that are in series. • Req = 45+50+100 = 195
10 30 iT i1 + 15 90 195 _ 5v 5 • Again using the loop on the far right. • The 90 and 195 resistors are in parallel. • Req= (90)(195)/(90+195) = 61.58
10 30 iT + 15 61.58 _ 5v 5 • Still working with the loop on the far right. • The 30 and the 61.58 resistors are in series. • Req = 30 + 61.58 = 91.58
10 iT + 15 91.58 _ 5v 5 • Again, the far right loop. • The 15 and 91.58 resistors are in parallel. • Req = (15)(91.58)/(15+91.58) = 12.9
10 iT + 12.9 _ 5v 5 • Now there is only one loop. • All the resistors are in series. • Req = 10+12.9+5 = 27.9
10 0.179A iT + + 12.9 27.9 _ 5v _ 5v 5 a • Use Ohm’s Law to determine iT. • iT = 5/27.9 = 0.179A • iT flows in all three resistors, the 12.9 resistor is the equivalent resistance of the entire circuit beyond points a and b. b
10 0.179A + 15 91.58 _ 5v 5 a ix • iT divides at a to flow through the 15 and the 91.58 resistors (the 91.58 is an equivalent resistance for the rest of the circuit). • Use current divider: ix = (0.179)(15)/(15+91.58) = 0.0252A.
10 30 0.179A + 15 61.58 _ 5v 5 a 0.0252A • No calculations are required at this step because the 0.0252A is flowing through both resistors in the right loop. • This circuit must be drawn however, because the 61.58 resistor is an equivalent for the circuit to the right of a and b. b
10 30 0.179A i1 + 15 90 195 _ 5v 5 a 0.0252A • Use the current divider equation again to determine i1. • i1 = (0.0252)(195)/(90+195) = 0.01724A = 17.24mA. • The current through the 195 resistor is 0.0252 - 0.01724 = 7.96mA b
One Minute Paper • please complete handout • no names • leave in box on leaving • thanks