Why Is My Calculated Voltage Across the 2k Resistor Incorrect?

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In summary, the voltage across the 2 kilo-ohm resistor in the circuit attached is -17.82 Volts. This does not match up with the answer guide which states that the voltage across the resistor should be -10.667 Volts. To solve this discrepancy, I used nodal analysis to find that the voltage across the resistor is Va (left node), which is 12mA<0 + Va/2Kohm - 2mA<0 + (Va - Vb)/1kohm = 0. Vb is 2mA<0 + (Vb - Va)/1Kohm + (Vb - 6Vx)/3.3Kohm = 0. This equation then tells me that the voltage across the resistor
  • #1
Number2Pencil
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in the circuit attached, find the voltage across the 2 kilo-ohm resistor.
I got -17.82 Volts<0...but that doesn't match up with the answer guide (-10.667Volts<0).



I used nodal analysis:

Va (left node): 12mA<0 + Va/2Kohm - 2mA<0 + (Va - Vb)/1kohm = 0
Vb : 2mA<0 + (Vb - Va)/1Kohm + (Vb - 6Vx)/3.3Kohm = 0
Dependent source supplemental: Va - Vb = Vx
 
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  • #2
Here is the circuit again...
 

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  • #3
Thread moved to the homework forums. Number2Pencil -- please do not post regular homework problems in the EE forum or other general forums. I think you should know better by now. I'll be back in a minute to try to offer some help on this homework question of yours.
 
  • #4
Double-check the sign convention you are using for Vx and the current through the 1k resistor...
 
  • #5
Hmm... I can't find any mistake on your part.
 
  • #6
doodle said:
Hmm... I can't find any mistake on your part.

Are you adding the currents into a node or out of a node?
 
  • #7
berkeman said:
Are you adding the currents into a node or out of a node?

He seems to be adding the currents leaving the node.
 
  • #8
berkeman said:
Are you adding the currents into a node or out of a node?

adding the currents leaving the node
 
  • #9
Number2Pencil said:
adding the currents leaving the node

Okay, your initial equations look correct. Can you show each step in your work that got you to your answer? If there's an error, it must be in there.
 
  • #10
sure: This is done in the TI-89

Solve( .012<0 + x/2000 - .002<0 + (x-y)/1000 = 0 , y)

ans ~> y this stores y as a function of x

Solve (.002<0 + (y - x)/1000 + ((y - 6(x - y))/3300) = 0 , x)

this is where I get -17.821 V <0.

I tried it with determinants and i think i got the same thing
 
  • #11
Yup, my answer's the same too. The given answer is possibly incorrect- that happens sometimes.
 
  • #12
Yup, I even had my teacher comfirm today that the book answer was wrong. I hate when this happens because it makes me second guess my way of doing these problems...

Thanks for the double checking everyone
 
  • #13
please send me a circuit diagram of termometer
 
  • #14
m_niknam said:
please send me a circuit diagram of termometer

Welcome to the Physics and Math Forums. Your post makes no sense -- can you please elaborate?
 

FAQ: Why Is My Calculated Voltage Across the 2k Resistor Incorrect?

What is circuit problem verification?

Circuit problem verification is the process of testing and ensuring the functionality of a circuit. This involves checking for any errors or malfunctions in the circuit design, components, and connections.

How is circuit problem verification performed?

Circuit problem verification is typically performed by using testing equipment, such as an oscilloscope or multimeter, to measure the voltage, current, and resistance at different points in the circuit. Simulation software can also be used to simulate the behavior of the circuit.

Why is circuit problem verification important?

Circuit problem verification is important because it ensures that the circuit will function as intended and can identify any potential issues that could lead to malfunctions or failures. This is especially crucial in critical systems, such as medical equipment or aerospace technology.

What are some common problems encountered during circuit problem verification?

Some common problems encountered during circuit problem verification include incorrect wiring or connections, faulty components, and incorrect values for resistors, capacitors, or other components. These issues can lead to circuit malfunctions or failures.

How can circuit problem verification be improved?

Circuit problem verification can be improved by using advanced testing techniques and tools, such as computer-aided design (CAD) software, which can help identify errors in the circuit design before it is built. Additionally, implementing a thorough testing and verification process can help catch any issues early on and ensure the circuit is functioning properly.

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