IPC
HS/Science
Unit: 11 Lesson: 01
EXPLORING SIMPLE CIRCUITS KEY
Symbols for drawing and reading circuit diagrams:Battery
– Usually marked with Voltage
(V)
•
Current flows out of (+) and into (-)
+
-
Resistor – Labeled in ohms (Ω)
Switch – Open switches mean no current will flow. Closed switches allow for
current to flow through the resistor.
Series Circuits:
The example below represents a series circuit. The electricity can only travel on one path. In this
series circuit design, three resistors (bulbs) are powered by a battery. Electricity can only flow from
the battery to each bulb, one at a time, in the order that they are wired to the circuit. Since electricity
can only flow in one path, if one bulb stops working, the other bulbs would also stop working because
the flow of electric current would be interrupted. Also, if one bulb was unscrewed, the flow of electrical
current to the other bulbs would be interrupted.
Parallel Circuits:
The example below represents a parallel circuit. The electricity can travel on more than one path. In
this parallel circuit design, three bulbs are powered by a battery. In this situation, if one of the bulbs
stops working, the other bulbs will still work because the electrical current to the broken bulb will not
interrupt the flow of electricity to the other bulbs. Also, if one bulb was unscrewed, the flow of
electrical current to the other bulbs would not be interrupted.
Materials:
• 6 volt battery
• flashlight bulbs with bulb holders (3 - 1.5)
• wires (10)
Directions: Label your bulbs (1–3), and then build the following circuits.
1. Create a series circuit with the three bulbs and the battery.
2. In the data table, describe the brightness of each bulb relative to high, medium, or low.
©2012, TESCCC
06/07/13
page 1 of 3
IPC
HS/Science
Unit: 11 Lesson: 01
3. In the data table, describe how the bulbs compare in brightness to each other. (Which is
brightest or same brightness?)
4. Unscrew one bulb in the series, and record what happens.
5. Repeat the procedure with only two bulbs in the circuit.
6. Repeat the procedure with only one bulb in the circuit.
SAMPLE DATA:
SERIES
Brightnes
s of Bulb
1
Brightnes
s of Bulb
2
Brightnes
s of Bulb
3
Brightness
of Bulbs Compared
to Each
Other
Circuit #1
(3 Bulbs)
Low
Low
Low
Same
Circuit #2
(2 Bulbs)
Medium
Medium
XXX
Same
Circuit #3
(1 bulb)
High
XXX
XXX
Parallel:
1. Create a parallel circuit with the three bulbs and the battery.
2. In the data table, describe the brightness of each bulb relative to high, medium, or low.
3. In the data table, describe how the bulbs compare in brightness to each other. (Which is
brightest or same brightness?)
4. Unscrew one bulb in the circuit and record what happens.
5. Repeat the procedure with only two bulbs parallel in the circuit.
6. Repeat the procedure with only one bulb in the circuit.
PARALLEL
Brightnes
s of Bulb
1
Brightnes
s of Bulb
2
Brightnes
s of Bulb
3
Brightness
of Bulbs Compared
to Each
Other
Circuit #1
(3 Bulbs)
Bright
Bright
Bright
Same
Circuit #2
(2 Bulbs)
Bright
Bright
XXX
Same
Bright
XXX
XXX
Same
Circuit #3
©2012, TESCCC
06/07/13
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IPC
HS/Science
Unit: 11 Lesson: 01
(1 Bulb)
Analysis:
1. How did the brightness of the three bulbs compare to each other when they were all connected
in series? They were all the same brightness.
2. How did the brightness of the bulbs change as the number of bulbs in the series circuit was
changed? Explain your reasoning. When the series had fewer bulbs, they were brighter than
when there were three bulbs. The brightness of the two bulbs was the same.
3. How did the brightness of the three bulbs compare to each other when they were all connected
in a parallel circuit? The bulbs were all very bright and equally bright.
4. How did the brightness of the bulbs change as the number of bulbs in the parallel circuit was
changed? Explain your reasoning. The brightness stayed the same. This is because each
bulb has direct access to the battery.
5. Which type of circuit will allow for the most energy to be used?
The parallel circuit allows for the most energy to be used.
©2012, TESCCC
06/07/13
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