There are two types of electrical circuits - series circuits and parallel circuits. A series circuit is a circuit that only has one path for the electricity to flow. If you look at the illustration, you see that the path goes from the battery, through one light bulb, through the second light bulb, and then back to the battery.
Remember from chapter 10.2, electrons are "pushing" each other. The illustration below is simplified for clarity.
One of the problems with a series circuit is if one bulb breaks (or is taken out), it creates an open circuit and even the good bulb cannot light. Notice that when the second bulb goes out, the first goes out also.
Which of the following statements are true about circuits?
(Note: the questions are multiple choice and multiple answer. The student will need to check all the correct answers. This keeps the student from just "guessing" at the answers.)
A parallel circuit is a circuit that has more than one path for the electricity to flow.
In this second illustration you will notice that when the first light bulb breaks (open circuit), the path to the second light is still there (closed circuit) and it continues to stay on.
Which of the following statements are true about circuits?
So now let's see how our understanding of series and parallel circuits applies with your circuit.
OBSERVATION
Sometimes, when a light bulb breaks in an electrical circuit, all of the bulbs on that circuit go out (like Christmas tree lights). However, other times a bulb may break but the rest of the lights in that circuit stay on.
HYPOTHESIS
What do you think will happen when you set up your circuit bulbs in a series circuit and then unscrew one light bulb?
Record your answer in the logbook!
GATHER THE FOLLOWING SUPPLIES
Circuit bag, the circuit alligator clips, battery holder.
STEP 1
Undo the wires on your circuit.
STEP 2
Wire your circuit as a series circuit. You will need the extra wire from your circuit bag (that you put in the bag when you made the circuit). Just line up the wires with the blue dotted lines as shown. Remember to tighten the screws again after you have re-wired it.
STEP 3
Note: the lights may be very dim when hooked up in a series circuit -- this is normal.
Now connect the battery holder to the circuit with the alligator clips as shown. Notice how the electricity will flow from the battery pack, through the two lights, and then back to the battery pack. A. Did both the light bulbs turn on?
Record your answer in the logbook!
STEP 4
Unscrew one of the light bulbs. B. Did the other light stay on? Explain why.
Record your answer in the logbook.
Now screw the light bulb back in.
STEP 5
Now wire your circuit as a parallel circuit. Just follow the red dotted lines. Put the third wire from the series circuit back into the circuit bag -- you will need it later.
STEP 6
Hook up the parallel circuit to the battery pack.
C. Did both lights turn on?
Record your answer in the logbook.
STEP 7
Unscrew a light bulb.
D. Did the remaining bulb stay on? Explain why.
Record your answer in the logbook.
STEP 8
Screw the light bulb back in.
THEORY
What would your theory be regarding series circuits versus parallel circuits? (Which do you think is most useful?)
Record your answer in the logbook.
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