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Variable resistance

by Warrzie
Tags: resistance, variable
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Warrzie
#1
Feb7-07, 09:25 PM
P: 3
1. The problem statement, all variables and given/known data
"A circuit has a variable resistance (total 100 ohms) across which is a voltage drop of 12 V supplied by a battery. What must be its resistance if the voltage is to be A) 12V and B) 6.2V?"

2. Relevant equations
V=IR


3. The attempt at a solution
We haven't learned anything besides Ohm's Law for these equations, so I tried plugging in different values to try and dial in the answers, but it didn't work. Is there something I'm missing or am I being asked to solve for two unknowns? Hints appreciated.
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denverdoc
#2
Feb7-07, 10:35 PM
P: 1,350
Is that all you have? Diagram? Im assuming total resistance is 100 ohms so for 12 v you have 8.5 amps. Then for 12V, you need a resistance of 12/8.5 but I dont trust this answer. If its a serial pair of resistors where Rx and Ry are 100 ohms and you are being asked the voltage drop across Rx, i think the above is good.
Warrzie
#3
Feb7-07, 10:38 PM
P: 3
Diagram

denverdoc
#4
Feb7-07, 10:43 PM
P: 1,350
Variable resistance

drawing a blank on the diagram, literally


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