Magnitude of the greater of 2 resistors?

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Homework Help Overview

The problem involves two resistors connected in series and parallel configurations with a given emf and current values. The objective is to determine the magnitude of the greater of the two resistances based on the provided conditions.

Discussion Character

  • Exploratory, Problem interpretation, Assumption checking

Approaches and Questions Raised

  • Participants discuss the application of equations for series and parallel circuits, noting the need for clarity in the original poster's work. There are questions about the original poster's understanding of the delta V equation and the process of solving for the resistances.

Discussion Status

The discussion is ongoing, with some participants suggesting a structured approach to derive the resistances from the equations. There is a recognition of the need for clearer work from the original poster to facilitate further assistance.

Contextual Notes

Participants note that the original poster's previous work is unclear and may contain errors, which complicates the discussion. There is an emphasis on the need for showing work to identify mistakes and clarify understanding.

Bearbull24.5
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Homework Statement


A 20 V emf is placed across 2 resistors in a series, a current of 2 A is present in each of the resistors. When the same emf is placed across the same 2 resistors in parallel, the current through the emf is 10 A. What is the magnitude of the greater of the 2 resistances?


Homework Equations


Series- I=I1=I2
delta V=I1R1+I2R2
Parallel- I=I1+I2


The Attempt at a Solution


I attempted to use the delta V equation, slightly off in my answer
 
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There is no way to tell if you made a little mistake - you haven't shown your work.
 
This was a question from a previous test and the work I have down is scrambled and makes little sense. Those were the equations I could pick out and I'm not even sure if I came up with my answer by working it through or I just picked an answer.
 
Bearbull24.5 said:

Homework Statement


A 20 V emf is placed across 2 resistors in a series, a current of 2 A is present in each of the resistors. When the same emf is placed across the same 2 resistors in parallel, the current through the emf is 10 A. What is the magnitude of the greater of the 2 resistances?


Homework Equations


Series- I=I1=I2
delta V=I1R1+I2R2
Parallel- I=I1+I2


The Attempt at a Solution


I attempted to use the delta V equation, slightly off in my answer

I don't know what a delta-V equation is.

Just write the two equations for the two cases given. You end up with two equations and two unknowns (R1 and R2). Solve for R2, and you get a quadratic equation. Solve the quadratic equation, and plug that back into the first equation to get R1.

Could you please show us work along the lines of what I've outlined for you?
 

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