Find the voltage V in the circuit

In summary, in order to solve this homework statement, you will need to simplify the circuit, compute the equivalent resistance of the two resistors in series, determine the current drawn by the voltage source, and solve for the voltage across the two resistors in parallel.
  • #1
matinm90
10
0

Homework Statement



we need to find V in this circuit. -see attachment

Homework Equations



how do I begin to simplify the circuit?

The Attempt at a Solution


 

Attachments

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  • #2
ok your given a 24 volt source in the middle.

by definition, any circuit component parallel to each other share the same voltage. this will mean that 24 volts will appear across the 12 ohm resistors in the middle.

from there you can try and determine the current and use Kirchoff current law to determine the loop currents. Hopefully you can then get the voltage you need

hope this helps
 
  • #3
funny u say that, my professor doesn't want us to use the kcl and kvl laws, basically no nodal or mesh analysis, which is why I am stuck, otherwise i can use those laws and figure it out in minutes.
 
  • #4
The diagram has been drawn so as to appear tricky, so redraw it with the source and each resistor laying vertical only for starters. You should only need the voltage divider equation (Ohms Law) to solve this.
 
  • #5
1. Simplify the circuit: four of the resistors can immediately be reduced to two.
2. Compute the equivalent resistance of the two R's in series & the one in parallel with those two.
3. You now have 1 voltage source in series with two resistors.
 
  • #6
matinm90 said:
funny u say that, my professor doesn't want us to use the kcl and kvl laws, basically no nodal or mesh analysis, which is why I am stuck, otherwise i can use those laws and figure it out in minutes.

The 6 ohm on extreme left and 12 ohm resistor on extreme right are parallel to each other.

Finding the combined parallel resistance would be a good start
 
  • #7
JamesGoh said:
ok your given a 24 volt source in the middle.

by definition, any circuit component parallel to each other share the same voltage. this will mean that 24 volts will appear across the 12 ohm resistors in the middle.
You haven't noticed that 4 ohm resistor on the source's -ve terminal?
 
  • #8
NascentOxygen said:
You haven't noticed that 4 ohm resistor on the source's -ve terminal?

yes i have but the 6 ohm and 12 ohm on the extreme left and right of the circuit still share two common nodes on the circuit. By definition this makes them parallel
 
  • #9
by definition, any circuit component parallel to each other share the same voltage. this will mean that 24 volts will appear across the 12 ohm resistors in the middle.

NascentOxygen was commenting in regards to the bolded bit, which is incorrect, as the source is in series with the 4R resistor and this entire branch is then in parallel with the 12R resistors on either side of it, meaning that 24 volts will NOT appear across the 12R resistors as stated.
 
  • #10
Sometimes it can be helpful to simply redraw the circuit, moving things about a bit (but not connections!) in order to bring out more familiar patterns. No analysis is required for this, just a bit of spatial imagination and manipulation.

For example, here's a version of the same circuit with things pushed about. Note that all the same component connections and nodes exist in this version; it is electrically identical to the original.

attachment.php?attachmentid=38876&stc=1&d=1316094169.gif


Parallel resistors are now obvious, so the obvious simplifications can be made there.

Those of you who know about Thevenin equivalents will recognize the opportunity to replace the part of the circuit left of red X's with its single source and resistor equivalent. Then you'll end up with a voltage source and three resistances in series. Easy-peasy.

Without Thevenin, KCL, or KVL, I suppose you can slog through the current calculations. Start by the net resistance seen by the voltage source and thus finding the total current that the source must drive through its 4 Ohm resistor, hence the voltage drop across it. This will tell you what the voltage is across the other two (parallel) branches. More current and voltage calculations... slog, slog, crank,... result.
 

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FAQ: Find the voltage V in the circuit

What is voltage?

Voltage is a measure of the difference in electric potential energy between two points in a circuit. It is often referred to as the "pressure" or "force" that drives electrons through a circuit.

How is voltage measured?

Voltage is measured in units of volts (V) using a voltmeter. A voltmeter is connected in parallel to the circuit and measures the potential difference between two points.

Why is it important to find the voltage in a circuit?

Finding the voltage in a circuit is important because it helps us understand the behavior of the circuit and how it will affect the components within it. It also allows us to calculate other important quantities like current and resistance.

What factors affect the voltage in a circuit?

The voltage in a circuit is affected by the power source, the resistance of the components in the circuit, and the arrangement of the components (series or parallel). Changes in any of these factors can result in a change in the overall voltage of the circuit.

How do you calculate the voltage in a circuit?

The voltage in a circuit can be calculated using Ohm's law, which states that voltage (V) is equal to current (I) multiplied by resistance (R). This can be represented by the equation V = IR. Alternatively, the voltage can also be calculated by measuring the potential difference between two points in a circuit using a voltmeter.

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