0
$\begingroup$

I am working on a physics equation on electrical circuits. I understand it in one direction but I am having issues looking at it backwards. I am given the following:

img R1 = R2 = R3 = 1.5 Ω

Calculate the equivalent resistance of the following circuit.

I can find equations when I am looking for the Req but I can't find any to find R1,R2,R3 given Req. If anyone wants to help or explain this it would be appreciated.

$\endgroup$

closed as off-topic by CuriousOne, Martin, AccidentalFourierTransform, user36790, Qmechanic May 9 '16 at 18:49

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Homework-like questions should ask about a specific physics concept and show some effort to work through the problem. We want our questions to be useful to the broader community, and to future users. See our meta site for more guidance on how to edit your question to make it better" – CuriousOne, Martin, AccidentalFourierTransform, Community, Qmechanic
If this question can be reworded to fit the rules in the help center, please edit the question.

1
$\begingroup$

$$R_{eq} =\frac R3$$
$$R = 3R_{eq}$$
when $$R_1=R_2=R_3=R$$

$\endgroup$
  • $\begingroup$ So the resistances are all equal? Different resistors don't have different resistances? Or is that only when regarding the amps? Also thank you very much for answering. $\endgroup$ – WJU May 9 '16 at 17:56
  • $\begingroup$ Sorry, I thought your question said they are all equal to 1.5 Ohms. If they are different then it is impossible to find R1, R2, R3 given only Req. You would need some extra information, eg that R1=(1/2)R2=(2/3)R3. $\endgroup$ – sammy gerbil May 9 '16 at 18:01
0
$\begingroup$

$R_1=1.5 \Omega$ , $R_2=1.5\Omega$ and $R_3=1.5\Omega$ gives you $$R_{eq} = \frac1{\frac1{1.5}+\frac1{1.5}+\frac1{1.5}}=\frac12=0.5 \Omega$$

You have to use this formula since the different resistors are parallel circuits.

$\endgroup$
  • $\begingroup$ I think she is just looking for equivalent resistance. So would it just be 1.5 x 3 = 4.5 Ω per resistor then 13.5Ω overall? Honestly this is starting to confuse me. (not your help, just electrical current in general) $\endgroup$ – WJU May 9 '16 at 18:05
  • $\begingroup$ From your question: "I can find equations when I am looking for the Req but I can't find any to find R1,R2,R3 given Req." So according to your question, you are looking for a formula for R1,R2,R3 when you know Req. I pointed out that it was impossible, and that you can find it if you know Req, R1, and R2. Maybe you misphrased your question? $\endgroup$ – wythagoras May 9 '16 at 18:09
  • $\begingroup$ Right from the worksheet it says what I put: Calculate the equivalent resistance of the following circuit. (above image goes here) R1 = R2 = R3 = 1.5 Ω $\endgroup$ – WJU May 9 '16 at 18:13
  • $\begingroup$ In that case your last sentence is very misleading. I will edit the answer. $\endgroup$ – wythagoras May 9 '16 at 18:14
  • $\begingroup$ I am very sorry, honestly, I appreciate your help. $\endgroup$ – WJU May 9 '16 at 18:15

Not the answer you're looking for? Browse other questions tagged or ask your own question.