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# HW2answers - P = 40 watts = V 2/R eq = 10 2(3R/2 and...

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HW 2 Redraw the figure as shown here: Then the 1 and 3 ohm resistors are in parallel with (3)(1)/(3+1) = 3/4 ohms and the 4 and 2 ohm resistors are in parallel with (4)(2)/(4+2) = 8/6 = 4/3 ohms. The final resistance is the sum of 3/4 + 4/3 ohms since they are in series. For n 1000 ohm resistors in parallel, we may find the total R = 1000/n - by inspection. 1 1) parallel R eq of 20 and 30 ohms = = (20)(30)/(20+30) = 600/50 = 12 ohms 2) the 12 ohms is in series with 8 ohms for an equivalent resistance of 20 ohms. 3) then the 20 ohms is in parallel with the 20 ohms on the right and the combination is an equivalent resistance of 10 ohms. 4) then this 10 ohms is in series with the 7 ohms resistor and sums to a final answer of 17 ohms . The parallel R’s have a resistance of R/2 and this R/2 in series with the R connected to the 10 V supply is a total

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Unformatted text preview: P = 40 watts = V 2 /R eq = 10 2 /(3R/2) and solving for R = 5/3 ohms . The 100 mA is flowing through R 2 and has 5 volts across it. R 2 = 5/.1 =50 ohms . R 2 has 5 volts across it and R 1 has 12-5 = 7 volts across it. R 1 = 7/.1 = 70 ohms . A 200 ohm resistor is added in parallel with R 2 and has an equivalent resistance of (200)(50)/(200+50) = 40 ohms. The voltage divider equation can be used to find v o = 12(40)/(70+40) = 4.36 volts . HW 2 2 The parallel resistors have an equivalent resistance of (15)(5)/(15+5) = 3.75 ohms. This 3.75 ohms has a current of 10 A flowing through it which makes the voltage across it (10)(3.75)=37.5 volts. Then i 3 = 37.5/5 = 7.5 amps . By inspection, the matrix equation is: 1 = 1/20+1/10 –1/10 v 1 2 = –1/10 1/5+1/10 v 2 1 = .15 –.1 v 1 2 = –.1 .3 v 2 v 1 = 14.29 i 1 =( v 1-v 2 )/10 v 2 = 11.43 i 1 = .286 amps...
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