I currently trying to train my skills in analyzing a Electric circuit using the node analysis and mesh method. But the answers I get isn't the same as the one giving. http://personal.georgiasouthern.edu...43-lec/exercises-quiz3-mesh-nodal-w-ans.pdf I tried calculating Exercise 1 and 5 using Node analysis. these are my calculations for exercise 1 http://snag.gy/Rfcp7.jpg And these are my calculations for excersice 5 Har også lige prøvet opgave 5 For V1 = 12v V2 = -2V I1 =6+(-3) = 3A V1 = 12V I2 = -1A -1 * 2 = -2V... And here is another one http://snag.gy/Dnuqf.jpg http://snag.gy/Rm2fs.jpg
You have here two unknown nodal voltages Vo and where we have 1Ω resistor Are you sure that this is a solution for exercise 5 For node V1 3A + V1/4Ω = 6A + (V2-V1)/1Ω And for V2 5A = V2/2Ω + 6A + (V2-V1)/1Ω And solution V1 = 4V l V2 = 2V http://www.wolframalpha.com/input/?i=3+%2B+V1%2F4+%3D+6+%2B+%28V2-V1%29%2F1%2C+5+%3D+V2%2F2+%2B+6+%2B+%28V2-V1%29%2F1+ You made a error in calculations X = - 12/11 http://www.wolframalpha.com/input/?i=(12+-+X)/6+++(0+-+X)/4+-+(X+-+(-6))/2+==+0
About exercise 1. I see there is 2 resistors for the voltage source at 40V. Are those 2 in series or parallel. The equation I wrote gave me V_0 to become 25,0714V. But thats incorrect?.. So should i change the resistors in parallel? About Exercise 5 I didn't know how i should use the node equation here, because i seemed to be simple. I shoudn't have thought so.. But using my knowlegde i get these equations. Are they correctly written? http://snag.gy/LWdjY.jpg And about the last one.. Yeah I see my mistake.. - to +.. Thanks for your reply.. I hope you help me with my other questions.
You can not do that because you have a 5A current source So we need to nodal equations for two unknown voltages V1 and Vo. No, you forget about current sources. For V1 node we can write I1 + I2 = I3 + I4 So we can write 3A + V1/4Ω = (V2-V1)/1Ω + 6A
Hmm, This current source has 1mA or 1A current ?? First I assume that all current flow into the Va node. And all current which entering the node are positive ( give them "+"). So I write 1mA + (-Va)/R3 + (Vo - Va)/R2 = 0 1mA - Va/510Ω + (0.5V - Va)/330Ω = 0 And the solution Va = 503.929mV As for your equations, you made slight error. (0.5 - V)/330 - (-V)/510 - 1 = 0 You also assume that all current entering into a Va node. but you assume that all entering currant are negative. So the correct nodal equations look like this: -(0.5 - V)/330 - (-V)/510 - 1 = 0 -(0.5 - V)/330 +(V)/510 - 1 = 0 Va = 200.661V Next time you should use this convention: Assume that all current flow out from the node and give them "+" if they flow out from the node. So we can write Va/R3 + (Va - Vo)/R2 + (-1A) = 0 Va/510 + (Va - 0.5)/330 -1A = 0 and solution Va = 200.661V