# What are the Unknowns in a KVL Circuit Loop?

• Engineering
• eatlsep
In summary, the conversation discusses the application of KVL and the calculation of voltage across resistors in a circuit. The equation V=IR is mentioned, and there is a disagreement about the correct answer for a specific problem. It is suggested to use another KVL loop to solve for the unknown voltages. Ultimately, it is concluded that Vr1 and Vr2 are not truly unknown, as they can be calculated using the known values of I1 and the respective resistors. The sum of the voltages around the left-side loop is also mentioned.
eatlsep
1.http://imgur.com/d2lf8sa

2. V=IR

3. I feel like the answer should just be .012 because 1.2/100. Apparently that is wrong. If that is truly wrong. I also found I3 to be 3.25mA because 3.9 volts in parallel and V=IR

What does Vs2 do to the voltage across R3?

Then apply KVL around the left hand loop.

Vs2 makes the voltage across R3 equal to Vs2? Then if I apply KVL to the left side I have 2 unknowns Vr1 and Vr2. Should I have another KVl loop?

eatlsep said:
Vs2 makes the voltage across R3 equal to Vs2? Then if I apply KVL to the left side I have 2 unknowns Vr1 and Vr2.
Write the equation for the sum of the voltages around the left-side loop.

The same current goes through R1 as R2.

eatlsep said:
Vs2 makes the voltage across R3 equal to Vs2? Then if I apply KVL to the left side I have 2 unknowns Vr1 and Vr2.

Vr1 and Vr2 aren't really "unknown"...

Vr1 = I1 * R1
Vr2 = I1 * R2

As we said, write the KVL equation for the left hand loop.

As I hinted earlier Vr3 = Vs2 (which is known).

Come back if still stuck.

## 1. What is a circuit diagram?

A circuit diagram is a visual representation of an electrical circuit, showing the components and how they are connected.

## 2. Why are circuit diagrams important?

Circuit diagrams are important because they allow us to understand the function and connections of a circuit without having to physically see or test it. They are also essential for troubleshooting and designing new circuits.

## 3. What are the symbols used in a circuit diagram?

The symbols used in a circuit diagram represent components such as resistors, capacitors, batteries, switches, and wires. They are standardized and help make circuit diagrams universally understandable.

## 4. How do I read a circuit diagram?

To read a circuit diagram, start at the power source and follow the path of the circuit, paying attention to the symbols and connections. The direction of the current flow is indicated by arrows, and the components are typically labeled with values or functions.

## 5. Can I make changes to a circuit diagram?

Yes, circuit diagrams are meant to be flexible and can be modified to fit your specific needs. However, it is important to understand the basics of circuit design before making any changes to ensure the circuit will function correctly.

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