Finding the Current Through a Resistor (Working With Parallel and Series)

[Oannes]

Homework Statement

What is the Current Through A Resistor in Parallel?

Relevant Equations

I = V/R
Resistors in Parallel => 1/R = 1/R1 + 1/R2
Resistors in Series => R = R1 + R2

Here is the actual question.

And here is my attempt at a solution

In Summary I did the following

1. Found the Equivalence Resistance to Be 5.9 ohms and the Current throughout the entire resistor to be 1.53 Amperes
2. Worked backwards from my resistor simplifications. When the resistors were in series I solved for V because they should have the same Current. When they were in parallel I solved for Current because they had the same voltage.
3. Eventually I worked my way back to the parallel resistors of 4.3 and 12 ohms and got .166 Amperes of current running through the 12 ohms resistor.
4. This answer, however, was wrong. I found this method from this video on Khan Academy https://www.khanacademy.org/science...-example-finding-current-voltage-in-a-circuit.

 

[TSny]

Your work looks correct to me. I carried an extra significant figure through the calculation and got an answer of 0.1679 A. But some of the resistors and the battery voltage are given with only 1 significant figure! So, I think two significant figures in the answer should suffice: 0.17 A.

 

[Oannes]

Your work looks correct to me. I carried an extra significant figure through the calculation and got an answer of 0.1679 A. But some of the resistors and the battery voltage are given with only 1 significant figure! So, I think two significant figures in the answer should suffice: 0.17 A.

You are exactly right thanks a bunch. I was going mad trying to figure out where i was going wrong.

 

[DaveE]

Yes, 0.168A