Electric Circuts (Voltage, Ohms, Amps)

[Kmcquiggan]

Homework Statement

Examine circuit and complete table and determine the power of the circuit.

Relevant Equations

v_1= I_1 R_1,I_3=I_4= I_T-I_2,R_T= V_T/I_T

I made a chart and this is my attempt. I am not sure that I am doing the calculations right thou

 

[phinds]

(1) Since there is no value for r3, the problem is unsolvable except as equations using r3 as the independent variable
(2) Show your work (I'm assuming YOU have a value for r3)

 

[Kmcquiggan]

No there is no value for R3

 

[phinds]

No there is no value for R3

Then your answers are all bogus.

 

[Kmcquiggan]

I was assuming because R3 and R4 are parallel that the values would be the same.

 

[phinds]

I was assuming because R3 and R4 are parallel that the values would be the same.

r3 and r4 are NOT in parallel, they are in series and there is zero reason to assume they have the same value whether they are series or parallel.

 

[Kmcquiggan]

Well there has to be a way to figure it out. It is the text and is required to be answered, so there has to be an answer. I can't just put can't find

 

[phinds]

Well there has to be a way to figure it out. It is the text and is required to be answered, so there has to be an answer. I can't just put can't find

As I have already said, it IS solvable, it's just that the answers will be equations using r3 as the independent variable

 

[ehild]

Well there has to be a way to figure it out. It is the text and is required to be answered, so there has to be an answer. I can't just put can't find

You know the voltage across R2. It is parallel with the chain R3 , R4, so the voltage is the same across the chain. You know the current through that chain. From the current, determine the voltage across R4. so you can get the voltage across R3.

 

[phinds]

You know the voltage across R2. It is parallel with the chain R3 , R4, so the voltage is the same across the chain. You know the current through that chain. From the current, determine the voltage across R4. so you can get the voltage across R3.

Good catch. I didn't even see the amperage figures.

 

[hutchphd]

Good catch. I didn't even see the amperage figures.

I was wondering!
OP: I believe you did everything correct except your assumption about R3 and therefore the voltage across it. Did you do the table like "cross word puzzle" or did you write down equations?. Either way is fine but learn to do both!

 

[Kmcquiggan]

I wrote down the equations and did them one by one on a scrap piece of paper. And thank you for the help :)

 

[Kmcquiggan]

You know the voltage across R2. It is parallel with the chain R3 , R4, so the voltage is the same across the chain. You know the current through that chain. From the current, determine the voltage across R4. so you can get the voltage across R3.

I am lost on how to find this. I was multiplying the resistance by the current? I am assuming that is not the formula

 

[ehild]

I am lost on how to find this. I was multiplying the resistance by the current? I am assuming that is not the formula

Why not?
Do you know Ohm's Law? The current through R4 is 0.06 A, The resistance R4 is 12 ohm. So what is the voltage across R4?