Current and Potential difference in a circuitby Xaspire88 Tags: circuit, current, difference, potential 

#1
Oct1007, 10:01 PM

P: 100

For the circuit shown find the current through and the potential difference across each resistor.
i was using the loop rules to make equations i could substitute into each other to solve this.. but i got stuck when i was making the last one for the currents... thus far i have I3= I4+I5 I1= I2+I3 and thus I1= I2+I4+I5 which then is 0=I1+I2+I4+I5 but i need to find one with all of the currents but i cant figure out what to substitute in to get an equations with I3 in it as well. Help please loop 1 0= I1R1 I3R3  I5R5 +24 loop 2 0= I1R1 I2R2 +24 loop 3 0= I2R2 +I3R3 +I4R4 +24 loop 4 0= I4R4 +I5R5 and then i need 0= the equation for the currents.. that way i can plug it into a simultaneous solver.. but im stuck 



#2
Oct1007, 11:56 PM

P: 210

I can't see the attachment. maybe you should upload to imageshack or something.




#3
Oct1007, 11:59 PM

P: 100





#4
Oct1107, 12:08 AM

P: 210

Current and Potential difference in a circuit
Ok, all this loop stuff is not necessary and according to me it adds confusion.
Use your seriesparallel formulae to reduce the circuit and systematically find the voltage drops and currents. circuits are usually reduced from the right to left when a single source is on the left. See what you can do. 



#5
Oct1107, 12:22 AM

P: 100

well i tried that at first. i determined the equivalent resistance of the circuit to figure out the current the first resistor would receive. i determined this to be 2 amps. the Req= 12 ohms.. but then i just seemed to get confused.. the current going into the first resistor equals that of the total current going into the rest of the resistors.. hmm




#6
Oct1107, 12:32 AM

P: 210

Ok so 2 amps through R1 so VR1 = 8V correct?
24V8V=16V which is the voltage across the rest of the circuit. hmmm can you see what to do from there? 



#7
Oct1107, 12:34 AM

P: 100

I think i have an idea :) 16V for the rest of the circuit, but doesn't the rest of the circuit also receive a total of 2amps? oh i see when it splits they both receive the same Voltage because they are in parallel. so the 24ohm resistor receives 16volts as does the Req of the other line.




#8
Oct1107, 12:43 AM

P: 210

Req should be 8 ohms not 12 ohms. go back and do it again and see where you went wrong.
and yes current from the 16 volts gives the rest of the circuit a total of 2 amps. 



#9
Oct1107, 12:49 AM

P: 100

im afraid i dont see
1/(1/8+1/24)+6= 12 1/(1/12+1/24)= 8 4+8=12? where did i go wrong? 



#10
Oct1107, 12:53 AM

P: 210

sorry. I assumed you didn't include R1 in Req. Nevermind what I said you are on the right track.




#11
Oct1107, 01:09 AM

P: 100

so from there i would gather that .... 16 volts goes to the 24ohm resistor 16V=Ix24 I=2/3A
16 volts goes to the other wire with a Req of 12 ohms. 16V= I 12ohms I= 1 1/3 amps.. 1 1/3 amps is the current that would go to each the 6 ohm resistor and the 6Req of the others. V= 1 1/3 amps x 6ohms V=8 volts ... 8 volts goes to each the 24 ohm resistor and the 8 ohm resistor since they are in parallel (had series typed). 8v= I24ohms I= 1/3 amps, and lastly 8V= I 8ohms I= 1 amp.. confusing possibly. but what do you think? 



#12
Oct1107, 01:19 AM

P: 210

I havent worked the values out myself but I do not see anything wrong with your method. everything looks good. amazing!
A good way to confirm your values is to use simulation software like circuit maker. Search for it. I think it is freeware since the company that made it went bankrupt. Simulation software will become very important as you progress through your course. 



#13
Oct1107, 01:24 AM

P: 100

yeah i think its right tried circuit maker earlier and got confused :) thanks for the help




#14
Oct1507, 05:14 AM

P: 1

This is what i got:
R1= 4 ohms, I1= 2A, V1= 8V drop R2= 24 ohms, I2= 2/3A, V2= 16V drop, R3= 6 ohms, I3= 4/3A, V3= 16V drop R4= 8 ohms, I4= 1/3A , V4= 16V drop R5= 24 ohms, I5= 1A , V5= 16V drop They should be right but im still not sure but i hope these answer will help. 


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