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Homework Help: Will there be a difference between the readings of V1 and V2

  1. Jul 19, 2017 #1
    • Poster reminded to use the Homework Help Template in the future for schoolwork posts
    I= Current flowing
    V1= Voltmeter 1
    V2= Voltmeter 2

    My question is that if there would be any difference between the readings of V1 and V2?
    We know that: By Ohm's law: V= I.R
    Combined resistance of R1 and R2 will be:
    1/RCombined Resistance of R1 and R2= 1/R1+1/R2
    The reading in V2 will be : (V2= I. Combined resistance of R1 and R2)
    But the current flowing in the circuit will get divided into two unknown parts at point C.
    Now, if the current I is being divided, then the reading of V1 should be different than V2.
    This is my problem please guide me.
  2. jcsd
  3. Jul 19, 2017 #2
    No. They will both give you a measurement equivalent to connecting the voltmeter between C and D.
  4. Jul 28, 2017 #3

    rude man

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    Lines on a schematic diagram are considered equipotentials. That ought to answer your question ipso facto.
  5. Jul 31, 2017 #4


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    You can determine the ratio from the fact that the potential is the same, which means that...
    ... no, it is divided in just such a way that V1and V2 are the same.
  6. Jul 31, 2017 #5


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    If you calculate the value of current (I) delivered by the battery cell, this value will be split so that a certain portion goes through r1, and the rest of the current goes through r2. The voltage measurements as you have configured will be practically the same, since the resistance of the wire is very low, compared to the components in the circuit.
    Refer to this table of wire resistances for typical sizes of copper wiring. If you are using 20 gauge wire, it will take 1000 feet of wire to result in 10 ohms of resistance. http://hyperphysics.phy-astr.gsu.edu/hbase/Tables/wirega.html
  7. Aug 1, 2017 #6


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    Another way of looking at it is to consider the length of the of wires. The length of A-C, C-E, B-D & D-F are not specified so they could have zero length. This would mean A and E are in the same physical and electrical place, B and F likewise. Then it's obvious V1 and V2 must be the same.
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