Designing a Circuit: Choosing Resistor Values for V = 5.5V

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Discussion Overview

The discussion revolves around a homework problem involving the selection of resistor values to achieve a voltage of 5.5V in a circuit. Participants explore methods for solving the problem, including the use of current dividers and voltage dividers, while expressing uncertainty about the provided information.

Discussion Character

  • Homework-related
  • Exploratory
  • Debate/contested

Main Points Raised

  • Some participants suggest using a current divider approach, indicating that the problem may require trial and error.
  • One participant questions the value of Is, suggesting that knowing Is is crucial to determining the necessary resistor values.
  • Another participant emphasizes the need for a known Vcc to apply the voltage divider concept effectively, stating that the problem lacks sufficient specificity.
  • A later reply points out that to find V, the relationship V = IR must be used, and that the circuit's parallel nature allows for a rearrangement of the equation to express Is in terms of R1 and R2.
  • Concerns are raised about the clarity of the problem statement, with participants indicating that it may be poorly explained or missing critical information.

Areas of Agreement / Disagreement

Participants express uncertainty regarding the adequacy of the problem statement and the necessity of additional information, particularly the value of Is. There is no consensus on how to proceed with the solution due to these ambiguities.

Contextual Notes

Limitations include the lack of a specified value for Is and Vcc, which are critical for solving the problem accurately. The discussion reflects varying interpretations of the circuit configuration and the relationships between voltage, current, and resistance.

dazedoutpinoy
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Homework Statement


Choosing from the following resistors values (they may be used more than once), set is, R1, R2, to obtain V = 5.5 V

[1 kilo ohm, 3.3 kilo ohm, 4.7 kilo ohm, 10 kilo ohm]


The Attempt at a Solution


I wasn't actually sure how to attempt this problem my textbook didn't really cover any examples of this. I included the figure needed to solve the problem, just any advice on how to start on it would be great.

http://img.photobucket.com/albums/v407/dazedoutpinoy/CircuitHomework001.jpg"
 
Last edited by a moderator:
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dazedoutpinoy said:

Homework Statement


Choosing from the following resistors values (they may be used more than once), set is, R1, R2, to obtain V = 5.5 V

[1 kilo ohm, 3.3 kilo ohm, 4.7 kilo ohm, 10 kilo ohm]


The Attempt at a Solution


I wasn't actually sure how to attempt this problem my textbook didn't really cover any examples of this. I included the figure needed to solve the problem, just any advice on how to start on it would be great.

http://img.photobucket.com/albums/v407/dazedoutpinoy/CircuitHomework001.jpg"


Use current divider. This problem is more of a trial & error.
 
Last edited by a moderator:
What is the value of Is? Once you know Is, then you know what R1 // R2 has to be.
 
V = IR

lol ... um, seriously, you can't really do anything with the values you did give. You would need to know your Vcc I'm guessing and then use a Voltage Divider...The question is way too inexact.
 
Something is wrong with this problem. Are you sure you didn't get a value for [tex]I_s[/tex]? Here's why I'm asking:

To find V you need:

[tex]V = IR[/tex]

Since the circuit you have is parallel, you can rewrite the above equation:

[tex]V = I_s(\frac{R_1R_2}{R_1 + R_2})[/tex]

Now re-arranging to solve for I:

[tex]I_s = \frac{V(R_1 + R_2)}{R_1R_2)}[/tex]

You have the value of [tex]V[/tex], and plugging in different values of [tex]R_1[/tex] and [tex]R_2[/tex] will simply give you different values of [tex]I_s[/tex], which would all be correct to the values of the resistors.

So either I'm missing something, or this problem is explained wrong.
 

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