Design a Circuit: Solve Homework Statement

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SUMMARY

The discussion revolves around designing a circuit using two ideal batteries with electromotive forces (EMFs) of 1.5 V and 9.0 V, along with three 120 Ω resistors, to achieve a current of 21 ± 1 mA through at least one resistor. The initial attempts included various configurations, such as series and multiloop circuits, but yielded currents outside the desired range. The successful solution involved placing the resistors in series and opposing the EMFs, resulting in a current of 21 mA calculated using the formula (9.0 V - 1.5 V) / 360 Ω.

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Electronics students, circuit designers, and hobbyists interested in practical circuit design and analysis, particularly those tackling homework problems involving ideal batteries and resistors.

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Homework Statement



You are given two ideal batteries with ##\epsilon_1 = 1.5 V## and ##\epsilon_2 = 9.0 V##. You are also given three ##120 \Omega## resistors.You may use any or all of the components. Design a circuit where there is a current of ##21 \pm 1 mA## through at least one of the resistors.

Do NOT use EMF sources in parallel.

Homework Equations


The Attempt at a Solution



I've already tried several combinations of resistors and batteries with no avail. The closest I've been is when all three resistors are in series with the ##9.0 V## emf. Then the current across the whole circuit is ##25 mA##. I've also tried creating several multiloop circuits, but those haven't worked either.

Anyone have some design advice? It would be very appreciated.

EDIT: Never mind guys I got it, just place the resistors in series and then oppose the emfs. Then the current is ##\frac{9.0-1.5}{360} = 21 mA##.
 
Last edited:
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glad to see you got it. I've never understood the utility of such problems, they just seem silly to me but I've seen them before.
 

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