# 8 when two resistors r1 1g1 and r2 1g2 are in series

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Unformatted text preview: re in parallel if they are connected to the same two nodes. Elements in parallel always have the same voltage across them (v1 = v2 ). 8. When two resistors R1 (= 1/G1 ) and R2 (= 1/G2 ) are in series, their equivalent resistance Req and equivalent conductance Geq are Req = R1 + R2 , Geq = G 1 G2 G1 + G 2 9. When two resistors R1 (= 1/G1 ) and R2 (= 1/G2 ) are in parallel, their equivalent resistance Req and equivalent conductance Geq are Req = R 1 R2 , R1 + R 2 Geq = G1 + G2 10. The voltage division principle for two resistors in series is v1 = R1 v, R1 + R 2 R2 v R1 + R 2 v2 = 11. The current division principle for two resistors in parallel is i1 = R2 i, R1 + R 2 i2 = R1 i R1 + R 2 12. The formulas for a delta-to-wye transformation are R1 = Rb Rc , Ra + R b + R c R3 = R2 = R c Ra Ra + R b + R c R a Rb Ra + R b + R c 13. The formulas for a wye-to-delta transformation are Ra = R1 R2 + R2 R3 + R3 R1 , R1 Rc = Rb = R1 R2 + R2 R3 + R3 R1 R2 R1 R2 + R2 R3 + R3 R1 R3 14. The basic laws covered in this chapter can be applied to the problems of electrical lighting and design of dc meters. REVIEW QUESTIONS | The reciprocal of resistance is: (a) voltage (b) current (c) conductance (d) coulombs v v 2.1 | e-Text Main Menu 2.2 | Textbook Table of Contents | An electric heater draws 10 A from a 120-V line. The resistance of the heater is: (a) 1200 (b) 120 (c) 12 (d) 1.2 Problem Solving Workbook Contents 61 62 PART 1 DC Circuits 2.3 The voltage drop across a 1.5-kW toaster that draws 12 A of current is: (a) 18 kV (b) 125 V (c) 120 V (d) 10.42 V 2.4 The maximum current that a 2W, 80 k safely conduct is: (a) 160 kA (b) 40 kA (c) 5 mA (d) 25 µA 2.9 Which of the circuits in Fig. 2.66 will give you Vab = 7 V? resistor can 5V +− 2.5 3V + − A network has 12 branches and 8 independent loops. How many nodes are there in the network? (a) 19 (b) 17 (c) 5 (d) 4 2.6 5V The current I in the circuit in Fig. 2.63 is: (a) −0.8 A (b) −0.2 A (c) 0.2 A (d) 0.8 A −+ b 1V 1V (a) (b) 5V 5V 3V + − +− + − b 3V + − +− I...
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