What are the equations for solving combined circuit problems?

AI Thread Summary
The discussion focuses on solving combined circuit problems using fundamental equations for series and parallel circuits. Key equations include IR=V for current and voltage relationships, and specific formulas for total voltage, current, and resistance in both configurations. Participants express confusion about identifying series and parallel resistors, particularly in a given circuit. Clarification is provided on how to analyze current flow to determine circuit configuration, emphasizing the importance of visualizing the circuit. Overall, the conversation highlights the need for practice and understanding of circuit analysis concepts.
j doe
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Homework Statement


14jpx0n.jpg


Homework Equations


IR=V
series circuit
Vt = V1 + V2 + V3...
It = I1 = I2 = I3...
Rt = R1 + R2 + R3...

parallel circuit
Vt = V1 = V2 = V3...
It = I1 + I2 + I3...
Rt = 1/R1 + 1/R2 + 1/R3...

The Attempt at a Solution


i honestly have no idea where to start. may someone pls help me?
 
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Can you identify any resistors which are in series and can be combined?
 
is 2 and 4 in a parallel circuit as well as 3 and 5?
 
Here is something which helped me a lot when I was solving circuits
"Analyse how he current flows.If you find the same current going into different resistors they are in series,If different current flow flow through them they are in parallel"
 
sidt36 said:
Here is something which helped me a lot when I was solving circuits
"Analyse how he current flows.If you find the same current going into different resistors they are in series,If different current flow flow through them they are in parallel"
i'm not sure how to tell that apart.
 
j doe said:
i'm not sure how to tell that apart.
When the current reaches the bottom end of resistor 5, where will it go?
 
phyzguy said:
When the current reaches the bottom end of resistor 5, where will it go?
back to resistor 1?
 
j doe said:
back to resistor 1?

No. I mean the bottom end of 5, in the lower right corner. The current flows down through 5, and then where?
 
phyzguy said:
No. I mean the bottom end of 5, in the lower right corner. The current flows down through 5, and then where?
oh to resistor 4?
 
  • #10
j doe said:
oh to resistor 4?

Right. And then when it leaves 4, where does it go?
 
  • #11
resistor 3 and when it leaves 3, it goes to 2? and when it leaves 2, it goes to 1?
 
  • #12
j doe said:
resistor 3 and when it leaves 3, it goes to 2? and when it leaves 2, it goes to 1?

Not quite. When it leaves 3, there are two places it can go. But, looking at sidt36's post #4, what can you say about 3, 4, and 5?
 
  • #13
3, 4, and 5 are parallel to each other. does that mean that 1 and 2 are series?
 
  • #14
j doe said:
3, 4, and 5 are parallel to each other

No! Read sidt36's post again.

does that mean that 1 and 2 are series?

No.
 
  • #15
phyzguy said:
No!
No.
is it the opposite?
 
  • #16
I'm not going to do the problem for you.
 
  • #17
phyzguy said:
I'm not going to do the problem for you.
yes, i understand that but i don't get what makes a circuit a series or parallel.
 
  • #18
upload_2016-5-26_8-24-15.png


Try making a diagram like this and check where the the current is going
 
  • #19
And I hope you don't mind if I ask which grade you are in because this should be pretty trivial for 10th grade student
 
  • #20
sidt36 said:
And I hope you don't mind if I ask which grade you are in because this should be pretty trivial for 10th grade student
i am in 10th grade and i recently just learned this
 
  • #21
j doe said:

Homework Statement


14jpx0n.jpg
:
:

The Attempt at a Solution


i honestly have no idea where to start. may someone pls help me?
You haven't stated what you are trying to solve for. What do you need to find? What is the actual problem statement?
 
  • #22
Well keep practicing
 
  • #23
I recommend a video
 
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