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Counting number of Branches in a Circuit

  1. Aug 11, 2010 #1
    In an electric circuit a branch is a part of the network between two points or junctions....

    I have attached a circuit diagram....Can anyone please confirm how many branches are there in the circuit.I m getting a little bit confused.
    I think the answer is 7. Plz tell me.

    V1=Emf source 1
    V2=Emf source 2
    R1=Resistance 1
    R2=Resistance 2
    R3=Resistance 3
     

    Attached Files:

  2. jcsd
  3. Aug 11, 2010 #2
    Can you upload a picture with you circling/labeling all of the different nodes (aka "points"/"junctions")? The answer is not 7, and you're probably counting a single node more than once.
     
  4. Aug 11, 2010 #3
    I have attached a picture which is circling the points or junctions.There are 6 nodes or points in total in the circuit.Hope that helps...
     

    Attached Files:

  5. Aug 11, 2010 #4

    Zryn

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    This may be slightly misleading. A circuit branch is more likely to be an area of equal potential energy, which could include many more than two points or junctions.

    For example, in the attached picture, in circuit A), there is only two branches (two areas of equal potential energy). Can you see why? Can you see how many branches are in circuit B) and C)?
     

    Attached Files:

  6. Aug 11, 2010 #5


    Can you please explain how there are only two branches? I am getting confused here.
     
  7. Aug 11, 2010 #6

    Zryn

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    Well, a node or branch is a point of equal potential energy.

    At the t junction in the centre of circuit A), if you measure the potential energy, you will get the same value everywhere you measure.

    If you go to the other side of any of the resistors or the voltage source, you will find the ground node. Irrespective of being drawn 4 different times, the ground node is a special node that is actually connected everywhere it is drawn (so you could draw wires all over the place and make the circuit look messy if you wanted to).

    Therefore, you have two different area's of potential energy, and thus two branches. See the picture attached with coloured in bits. Notice mine are big area's and your are small circles. If you can expand your circles to encompass all the wire between each set of two (or more) componants you will be doing better.

    Edit: The point where two wires meet is not necessarily enough of a reason to call something a circuit branch. You could have 1 million wires like spokes in a wheel all branching out from the same centre point, and that would still be only 1 circuit branch, because all those wires have the same potential energy.
     

    Attached Files:

    Last edited: Aug 11, 2010
  8. Aug 11, 2010 #7
    zryn is wrong. a branch is different from a node/junction/point of equal potential. There are FOUR branches in his example where he claimed there are only 2 branches. There are, however, only two nodes.

    I don't understand where you are getting 7 from. Can you upload a picture circling what you believe to be 7 branches? That way, I can specifically dispel your confusion by viewing it first.

    also, the three circles at the bottom in that circuit you uploaded, write2diba, are all the same node. You seem to think there are 6 different nodes when there are only 4.
     
  9. Aug 11, 2010 #8

    Zryn

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    I was under the impression the original poster is doing analysis in regards to voltages and not currents. If this is not the case then my apologies for confusing the situation!
     
  10. Aug 14, 2010 #9
    Wait wait......I am totally in confusion now........First anyone tell me how many nodes are there in my picture that I posted originally and how.......
     
  11. Aug 14, 2010 #10

    Zryn

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    When you say nodes (voltages), everything I said is correct. When you say branches (current) then disregard what I said and listen to 'xcvxcvvc'.

    Do you know which it is you need (node voltages OR branch currents) ? In your first post you asked for branches and your last post asked for nodes.
     
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