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Ratio of Resistors

1. Homework Statement

Two resistors of resistances R_1 and R_2, with R_2 > R_1, are connected to a voltage source with voltage V_0. When the resistors are connected in series, the current is I_s. When the resistors are connected in parallel, the current I_p from the source is equal to 10 I_s.

Let r be the ratio R_1 / R_2. Find r.

2. Homework Equations

In series R = R1 + ... + RN
In parallel 1 / R = 1 / R1 + ... + 1 / RN

3. The Attempt at a Solution

I_s (R_1 + R_2) = 10 I_s (R_1 * R_2) / (R_1 + R_2)

0 = R_1^2 - 8 R_1 R_2 + R_2^2

Quadraxtic equation R_1 = 4 +/- sqrt(9 - R_2)

I don't know quite what to do now

I need that ratio but it is just dirty

(4 + sqrt(9 - R_2)) / R_2

Help very much appreciated
 

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