1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Is this circuit the same as this?

  1. Mar 27, 2014 #1
    The circuit includes three identical light bulbs and a capactior that is fully charged. The power supply provides a steady potential difference. Which light bulb(s) is brightest? I attached the diagrams.

    My answer is C. Either that or A and B.
    Are my rewritten drawings equivalent to the original?

    Attached Files:

  2. jcsd
  3. Mar 27, 2014 #2


    User Avatar
    Gold Member

    Consider: What's the voltage drop across Resistor A, B, C and the capacitor in the origional. Then compare that to the other 2. Remember wire has a 'negligible' resistance, so across bare wire the potential has to be the same. I'm not answering your homework for you, though.
  4. Mar 27, 2014 #3
    in the original diagram, after current flows through A and through B, it has to go through the horizontal bar in the middle. What happens there, do they cancel?
  5. Mar 27, 2014 #4


    User Avatar
    Gold Member

    Does current flow through the middle? Current flows from higher potential to lower potential, right? Kind of like a ball at the top of a "potential hill". Label the left junction point 1 and label the right junction point 2 and figure out what the potential is at the points. Then post the current between the to points.
    *Edit: The junctions after A and B respectively
    Last edited: Mar 27, 2014
  6. Mar 27, 2014 #5
    Can I pretend the capacitor isn't there since it's fully charged?
    And if I do, would A+B be in series with C?
  7. Mar 27, 2014 #6
    Yes, and yes.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted