# Current and Potential difference in a circuit

by Xaspire88
Tags: circuit, current, difference, potential
 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 Attached Thumbnails
 P: 210 I can't see the attachment. maybe you should upload to imageshack or something.
 P: 100 http://img77.imageshack.us/content.p...circuitus9.jpg there is the link to the img file
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 series-parallel 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.
 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
 P: 210 Ok so 2 amps through R1 so VR1 = 8V correct? 24V-8V=16V which is the voltage across the rest of the circuit. hmmm can you see what to do from there?
 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.
 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.
 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?
 P: 210 sorry. I assumed you didn't include R1 in Req. Nevermind what I said you are on the right track.
 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?
 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.
 P: 100 yeah i think its right tried circuit maker earlier and got confused :) thanks for the help
 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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