I have two problems that have been bothering me, which I just cannot seem to figure out. Both have to do with current in a DC circuit with multiple resistors.(adsbygoogle = window.adsbygoogle || []).push({});

The first one looks like this:

12 V 4 ohms

|------:|:|-----\/\/\-----|

| |

| 18 V 12 ohms |

a|------:|:|----\/\/\------|b

| 8 ohms |

|-----------\/\/\---------|

I am trying to find the current through the 4 ohm resistor, but I am not quite sure how to go about doing so. I tried subtracting the voltages since they are in parallel and finding the equivalent resistance and then using Ohm's Law, but that was unsuccessful. I have a feeling it might intend for me to use Kirchoff's rules, so I then tried doing so from junction a to junction b. I got V_{ab}=16-4I_{1}=18-12I_{2}=8(I_{1}-I_{2}(I_{1}is from b to a around the top, where the 16 V and 4 ohm resistor is, I_{2}is from b to a directly across the middle, and I_{3}is from b to a along the bottom, where the 8 ohm resistor is), but just didn't know where to go from there. Would the current be I_{1}, or something else?

The second problem is quite similar. In this one, I am trying to find the power given off my one of the 10 ohm resistors; I think my problem here is again the current, as power=I^2 * R.

It looks like this:

12 V

|-----:|:|-------------|

| |

| |

| 2 ohms |--\/\----| <----20 ohms

|---\/\------|---\/\---| <----10 ohms

|---\/\---| <----10 ohms

So basically I am trying to find the current through one of the 10 ohm resistors so I can use it to find power, which is I^2 * R.

I would really appreciate some help on this, as I am studying for a test, and these two problems have been troubling me for much too long.

Thanks!

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# Homework Help: Current and Power in DC Circuits

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