Calculating Current and Voltage in a Series Resistor Circuit

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Homework Help Overview

The discussion revolves around calculating current and voltage in a series resistor circuit, with the original poster attempting to determine the values of currents (Ia, Ib, Ic) and voltages (Va, Vb, Vc) at different points in the circuit based on a given voltage source (Vs) and resistances (R1, R2).

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants explore the relationship between current and voltage in a series circuit, questioning the original poster's assumptions about equal voltage at all points and the application of Ohm's law. There is also discussion about the implications of changing the circuit configuration to a parallel arrangement.

Discussion Status

Some participants provide clarifications regarding the behavior of current and voltage in series circuits, emphasizing that current remains constant while voltage drops across components. There is ongoing exploration of how these principles would change if the circuit were modified to include parallel components.

Contextual Notes

The original poster's understanding of circuit behavior appears to be based on a misunderstanding of voltage distribution in series circuits, and there is a suggestion to reconsider the implications of circuit configuration changes.

Midas_Touch
|------A------|
|.....* R2
- Vs.....|B
-.....|
|.....* R1
|------C----- |

Assuming that the above is a circuit (sorry for the bad drawing, ignore the dots), what would be Ia, Ib, Ic (currents), Va, Vb, Vc (voltages)? Initially, I thought that the current and the voltage would be the same at all points.

I know that Req is equal to the sum of R1 and R2 (resistance). So would Ia be Vs/(R1*R2)? Would Ib be Vs/R2? and Ic, Vs/R1?

For the voltages, I think that it is equal to Vs at points A,B,C. But, I am not sure.

I'd appreciate some feedback. Thanks.
 
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In a series circiut the current is the same at all points, not the voltage. Use Ohms law to find the voltage at each point, given the constant current. Your total voltage drop should equal the source voltage.
 
Interestingly you are using two correct concepts, but not applied to the correct variable.

It is the voltage (potential) that starts off at a value (Vs) and in a series circuit, drops some amount through each component, until it reaches its lowest value (typically ground = 0v).

The other variable current, in a series arrangement, does not drop but stays the same through each component.

This will be different in a parallel arrangement, and I will let you figure that one out.. Applying what I gave you above, try this one again..
 
Last edited:
Integral said:
In a series circiut the current is the same at all points, not the voltage. Use Ohms law to find the voltage at each point, given the constant current. Your total voltage drop should equal the source voltage.

How about if R2 was parallel to R1? Would the current still be the same and the voltage be different at points around the circuit?
 
Midas_Touch said:
How about if R2 was parallel to R1? Would the current still be the same and the voltage be different at points around the circuit?
See my last post, and you should be able to deduce your answer.
 
Midas_Touch said:
How about if R2 was parallel to R1? Would the current still be the same and the voltage be different at points around the circuit?
If R2 were parallel to R1 then it would not be a series circuit would it? Why do you expect a parallel circuit to behave the same as a series?
 

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