Circuit Problem: MCAT physics

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premedsp

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This question is relating to a video from the Premed HQ channel (youtube channel).

How is the answer 4 ohms? I see the series at the top which equals 4 ohms. That series is then in combination with the parallel resistor and gets us 1/2 ohms. I not sure where to go from there.


Video credit:
Screen Shot 2021-01-07 at 9.07.36 PM.png

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This is a really easy mistake to make :). The total resistance term for the circuit component on top isn't 1/2 ohms, it is 1 over (2 ohms), since the equation is 1/R1 + 1/R2 = 1/Rtotal. I attached a screenshot with more intuitively aligned equations, which should help make this clear.
 

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  • Screen Shot 2021-01-08 at 11.01.13 AM.png
    Screen Shot 2021-01-08 at 11.01.13 AM.png
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