Tuesday, May 18, 2010


A DC circuit, or direct current circuit, is a path for which a flow of charge passes.  It usually consists of a source and a load.  The source provides energy for the charged flow to carry to the load (a light bulb or motor, etc.) and back to the negative end of the source.  It also needs to be in a closed path to be a circuit.

This light bulb is in series.  The current in this is pretty simple.  The flow of charge exits the positive end of the source, the battery, and makes its way to the light bulb.  It then goes back to the negative end of the battery.  Since the bulb is in series, the current will stay the same throughout the whole thing.  Since there is only one bulb, the voltage will be the current in amperes multiplied by the resistance of the bulb in ohms.

These bulbs are in parallel.  This is different from series because the current acts different.  There is more amperes of current in the bulb closest to the battery than the one above.  Also unlike series the voltage between the two bulbs remains the same.  This is because the potential difference for light bulbs in parallel are the same.  This is a very interesting circuit.

This circuit is a complex of two light bulbs ins parallel and one in series.  As you can see in the picture above, the bulb in series is brighter than the ones in parallel, which have the same brightness.  This is because the voltage of the bulb in series is greater than the ones in parallel.  The bulbs in parallel however still have the same voltage.  The current through this kind of circuit is strange in that each bulb will have its own separate current.

1 comment:

  1. Great job with your diagrams.
    Your explanation of how a circuit works is perfect!
    The current in the series circuit is clearly explained but the explanation of voltage is missing.
    In the parallel circuit you said that current acts different, I know that you probably meant that now there are two paths for the current to flow. However, you said that there is more current in the bulb closest to the battery. This is not necessarily the case as it depends on the resistance of the light bulb.
    You do a good job highlighting the different brightnesses of the bulbs in the complex circuit but you don't clarify why voltage across the elements is the way it is and you did not offer an explanation of the current.
    Be sure that you understand how this works as circuits are an important part of the final exam.