Current and Potential difference in a circuit

In summary, the current through the circuit is I1= I2+I3, the potential difference across each resistor is V1-V2=V3-V4=V5, and the voltage across each resistor is V1+V2+V3+V4+V5.
  • #1
Xaspire88
100
0
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 can't figure out what to substitute into 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 I am stuck
 

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  • #2
I can't see the attachment. maybe you should upload to imageshack or something.
 
  • #3
http://img77.imageshack.us/content.php?page=done&l=img77/4002/circuitus9.jpg [Broken]

there is the link to the img file
 
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  • #4
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.
 
  • #5
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
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?
 
  • #7
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.
 
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  • #8
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
im afraid i don't see

1/(1/8+1/24)+6= 12

1/(1/12+1/24)= 8

4+8=12?

where did i go wrong?
 
  • #10
sorry. I assumed you didn't include R1 in Req. Nevermind what I said you are on the right track.
 
  • #11
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?
 
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  • #12
I haven't 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
yeah i think its right tried circuit maker earlier and got confused :) thanks for the help
 
  • #14
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 I am still not sure but i hope these answer will help.
 

1. What is the difference between current and potential difference in a circuit?

Current refers to the flow of electric charge through a circuit, while potential difference (also known as voltage) measures the difference in electric potential between two points in a circuit. In other words, current is the movement of electrons, while potential difference is the force that drives those electrons.

2. How is current and potential difference related?

Current and potential difference are directly proportional to each other according to Ohm's Law. This means that as potential difference increases, so does current. However, this relationship can be affected by factors such as resistance and circuit components.

3. What are the units of measurement for current and potential difference?

Current is measured in amperes (A) and potential difference is measured in volts (V). In a circuit, current is typically measured using an ammeter, while potential difference is measured using a voltmeter.

4. How does the direction of current flow relate to potential difference in a circuit?

The direction of current flow is determined by the potential difference in a circuit. Current flows from areas of high potential (positive terminal) to areas of low potential (negative terminal). This is why the direction of current is often depicted as moving from the positive to the negative terminal.

5. What is the difference between AC and DC current in terms of potential difference?

AC (alternating current) and DC (direct current) differ in terms of their potential difference. In AC circuits, the potential difference constantly changes direction, while in DC circuits, the potential difference remains constant. This is why AC circuits are often used to power homes and appliances, while DC circuits are used in electronic devices.

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