Series DC Worksheet Question 27

Discussion in 'General Electronics Chat' started by Legion6789, Feb 8, 2014.

  1. Legion6789

    Thread Starter New Member

    Feb 8, 2014
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    I was able to figure out everything correctly except for R4 as a suspected short. I had it as a possible open.

    I can't figure out how measuring 6V from terminal 1 to 8 marks R4 as a possible short instead of a possible open. Can someone explain?
     
  2. ScottWang

    Moderator

    Aug 23, 2012
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  3. Legion6789

    Thread Starter New Member

    Feb 8, 2014
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    Yeah, that's the page. Thanks.
     
  4. ScottWang

    Moderator

    Aug 23, 2012
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    I can't get your point?
    Are you asking the V or I from the R4 resistor or what?
     
  5. Legion6789

    Thread Starter New Member

    Feb 8, 2014
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    The question states that a technician took 3 voltage measurements to try and track down the fault in the circuit. For each voltage measurement you're supposed to fill in the appropriate row in the table with what you can infer from the voltage measurement.

    The first measurement is between terminal 1 and 8 and shows a 6V difference. So we know the battery is ok and the wires connecting the battery to terminals 1 and 8 are ok too. So that narrows down the fault to somewhere between R1 and R4.

    The first row in the answer table shows that any of the components between terminal 1 and 8 could have an open fault. Except for R4 which it lists as a possible short. That's what I don't understand. Why is R4 listed as a possible short instead of a possible open fault?
     
  6. ifixit

    Distinguished Member

    Nov 20, 2008
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    1. The first line in the question states: there is no voltage output between terminals 7 and 8
    2. The text also states that there is only one fault.
    3. This means that either R4 is shorted or there is an open elsewhere in the circuit.
     
  7. Legion6789

    Thread Starter New Member

    Feb 8, 2014
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    Thanks ifixit, I totally missed that first line about no voltage output between 7 and 8. Makes sense now. Thanks!
     
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