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Homework Help: Is voltage and amp constant in a current?

  1. Jan 7, 2012 #1
    Lets suppose a current has a battery, and two light bulbs connected in series. If I measure the voltage on the piece of wire before and after the two light bulbs, will they be the same? And if I measure the amp at these same location, will they also be the same?

    I know that if I connect volt or amp meter between the light bulb, there will be a drop. Right?

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  2. jcsd
  3. Jan 7, 2012 #2
    If V and I are voltmeter and ammeter then,
    First, I is connected in series with circuit
    Second, wires in a traditional circuit are considered perfectly conducting, But still if you assume that there is some resistance on wires then the voltage will come out to be same if their lengths are same, and of course their geometry is same,
  4. Jan 7, 2012 #3


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    Staff: Mentor

    The voltage will drop as you work your way around a circuit. If the bulbs are identical, then midway, i.e., between the two light bulbs, the voltage will be about half of the battery voltage. You should note that voltage is not measured by inserting a meter in series with the components in a circuit. Voltage is measured by connecting a voltmeter in parallel with the components whose voltage you wish to measure. Voltmeters are designed to have a high resistance, so they draw very little current away from your circuit and thus have practically no ill effect on it.

    The current is constant all around the circuit. It doesn't matter where you connect the meter, in a series circuit the meter will give the same reading. Ammeters have to be connected in series with the component whose current you wish to measure. Ammeters are designed to have very low resistance, so they have very little adverse effect on the operation of your circuit.
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