Finding the current and voltage for each resistor

In summary: The current in the river is the sum of the currents in the left and right channels.In summary, the student is trying to solve a problem involving current and voltage, but is having difficulty understanding the rules governing these calculations. The student has correctly calculated the current through R1 and R2, but incorrectly calculated the current through R3. The student is new to circuits, and may benefit from learning more about how currents flow in general.
  • #1
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Homework Statement


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Homework Equations


V=IR
Series in parallel
Series in current

The Attempt at a Solution


I managed to get the current and voltage of R1 and R2. I've been trying to get the next one R3, but haven't had success. I tried following the drawing, but couldn't figure out what I'm doing wrong. I thought that the current of R1 would be the current of R3. But I checked it against the solutions and it is incorrect.
 

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  • #2
The current through R2 plus R3 will equal the current in R1.
The current through R4 plus R5 will equal the current in R3.

Reading your work, all of your resistance calculations are correct.
 
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  • #3
Your only mistake so far is thinking that the current through R1 and R3 are equal.
 
  • #4
Why does the current through R2 and R3 equal the current in R1? Does it have to do with the junction? And then I can't figure out R4 and R5 since I am unsure of what rule to follow. I figured out R3 would be I=.15, R=.75 .
Also, the reason I thought R1 and R3 current would be equal was because of the rule that in series currents are the same. But i guess R2 interrupts that rule?
 
  • #5
Here's the rule: At any junction, there will be as much current flowing in as there is flowing out.
It in and out are given opposite signs (plus/minus), then the current at the junction will always add up to zero.
 
  • #6
Prescripted, it seems you are new to circuits. It generally takes a while to realize that the assignment of the term "current" to the flow of charges was quite accurate. Thinking of a river can help you understand. After that it might be better to forget thinking of the flow of water. It does not apply to well to all cases. But it does here.

Assume we are talking about positive charge carriers. That way (as opposed to how electrons flow) the current comes out of the battery and heads for R1. After going thru R1, the charges have a choice. The current divides, some going thru R2 and some go thru R3. That is why the current through R2 + the current thru R3 equal the current in R1. Think of a river with a large island in it. Some of the water goes left, the rest goes right.
 

Related to Finding the current and voltage for each resistor

1. How do I find the current for each resistor in a circuit?

To find the current for each resistor, you can use Ohm's Law which states that current (I) is equal to voltage (V) divided by resistance (R). So, you can calculate the current by dividing the voltage across the resistor by its resistance.

2. Can I use Kirchhoff's Laws to find the current for each resistor?

Yes, you can use Kirchhoff's Laws, specifically Kirchhoff's Current Law, to find the current for each resistor. This law states that the total current entering a junction must equal the total current leaving the junction.

3. What is the difference between current and voltage in a circuit?

Current is the flow of electric charge through a conductor, while voltage is the potential difference between two points in a circuit. In other words, current is the movement of electrons, while voltage is the force that drives the movement.

4. How do I calculate the voltage for each resistor in a series circuit?

In a series circuit, the total voltage is divided among the resistors. To calculate the voltage for each resistor, you can use Ohm's Law again, but this time, the voltage (V) will be equal to the current (I) multiplied by the resistance (R).

5. What happens to the current and voltage in a parallel circuit?

In a parallel circuit, the voltage remains the same across each resistor, while the current is divided among the resistors. This means that the total current entering the circuit is equal to the sum of the currents through each resistor.

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