Combined Circuit problem

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In summary, the conversation is discussing the placement of a voltmeter in a circuit and how to find the voltage using the voltmeter. The solution involves finding the voltage at different points in the circuit and taking the difference between these values. However, there is no indication of which terminal of the voltmeter is positive or negative, so the final answer may be positive or negative depending on how the probes are connected.
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Homework Statement


I am having trouble with the placement of the voltmeter in this particular problem


Homework Equations


What is the reading on the voltmeter V?

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The Attempt at a Solution


I found that the resistance of R is 8 ohms and the current flowing through it is 7.5 A. But I don't know how to find the voltage when the voltmeter is placed in that way :confused: I have only done voltage when the voltmeter is placed in parallel with a singular resistor only.
 
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  • #2
The voltage at the left side of the 4 ohm resistor is 100.0V, relative to Y. What is the voltage at the right side of the 4.0-ohm resistor, relative to Y? This will be the voltage appearing at the "+" terminal of your voltmeter.

The voltage at the left side of the 1 ohm resistor is also 100.0V relative to Y. What is the voltage at the right side of the 1.0 ohm resistor, relative to Y? This will be the voltage appearing at the "-" terminal of your voltmeter.

Now your voltmeter is measuring the difference of these 2 voltages (V4-ohms, right side - V1-ohms, right side)
 
  • #3
lewando said:
The voltage at the left side of the 4 ohm resistor is 100.0V, relative to Y. What is the voltage at the right side of the 4.0-ohm resistor, relative to Y? This will be the voltage appearing at the "+" terminal of your voltmeter.

The voltage at the left side of the 1 ohm resistor is also 100.0V relative to Y. What is the voltage at the right side of the 1.0 ohm resistor, relative to Y? This will be the voltage appearing at the "-" terminal of your voltmeter.

Now your voltmeter is measuring the difference of these 2 voltages (V4-ohms, right side - V1-ohms, right side)

Well said, except that there is no indication as to which terminal of the voltmeter is positive and which is negative. Therefore, the answer may be either positive or negative, depending on the orientation of the voltmeter (how the probes are connected).
 

1. What is a combined circuit problem?

A combined circuit problem is a type of electrical circuit problem that involves multiple components, such as resistors, capacitors, and inductors, connected in a complex arrangement. These circuits can be analyzed using various techniques, such as Kirchhoff's laws and Ohm's law, to determine the behavior of the circuit and solve for unknown values.

2. How do I approach solving a combined circuit problem?

The first step in solving a combined circuit problem is to carefully draw out the circuit diagram and label all known values and components. Then, you can use the applicable laws and equations to analyze the circuit and solve for the unknown values. It is important to use a systematic approach and double-check your calculations to ensure accuracy.

3. What are the most common challenges when solving a combined circuit problem?

One common challenge when solving a combined circuit problem is identifying the correct equations and laws to use in the analysis. It can also be difficult to keep track of all the different components and their values, especially in more complex circuits. Additionally, it is important to be aware of any simplifying assumptions that may have been made in the problem.

4. Can software or calculators be used to solve combined circuit problems?

Yes, there are various software programs and online calculators available that can help with solving combined circuit problems. These tools can help with organizing the circuit diagram and performing the necessary calculations. However, it is important to understand the underlying principles and equations to ensure accurate results.

5. How can I check my solution for a combined circuit problem?

One way to check your solution for a combined circuit problem is to use the laws of conservation of energy and charge. The sum of all the voltage drops in a circuit should equal the total voltage supplied, and the sum of all the currents should equal the total current entering the circuit. Additionally, you can use a multimeter to measure the voltage and current at different points in the circuit and compare them to your calculated values.

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