NESA Spring Educators Conference
March 31- April 3, 2012 - Athens, Greece
Scientific Inquiry and
Technology-Based
Inquiry
Maya Mouhaidly Simon Barakat
Facilitator,
Middle
School
Science
Science teacher, Middle School
G8 teacher
American Community School at Beirut American Community School at Beirut
mmouhaidly@acs.edu.lb sbarakat@acs.edu.lb
The American Community School at Beirut
Science Department
Grade 8
Parallel and Series Circuits- Lab Activity
Name:_____________________
Section:_________
Date:_______
Laboratory Objectives:
 To understand series and parallel circuit connections.
 Learn how to connect meters for reading current and voltage.
 Understand how voltage and current behave in a series and parallel circuit
Introduction:
In a series circuit there is only one path for the flow of charge, or current,
as it leaves the power supply and travels through the circuit. Therefore all
of the current from the power supply travels through each circuit component
(light bulbs for example).
An ammeter is used to measure the amount of current (in amps or milliamps)
flowing in a circuit. An ammeter is always connected in series with the
circuit component you are measuring.
A voltmeter is used to measure potential energy difference, voltage (in volts
or millivolts) across a circuit component. A voltmeter is always connected in
parallel with the circuit component you are measuring.
Materials:
3 light bulbs, 3 light bulbs stands, 6 alligator clip wires, 6V battery,
multi-meter.
Procedure:
Simple Circuit:
1. Build a simple circuit using 1 light bulb, 2 alligator clip wires, and a 6V
battery. Observe the brightness of the bulb and draw your circuit in the
space below:
Series circuits:
2. Add another light bulb in series with the first one. Draw your circuit in the
space below and compare the brightness of the 2 bulbs to the one light bulb
in step one. Record your observation in the data table.
Measuring Voltage in a series circuit:
a. Using the voltmeter, measure the total voltage of the battery.
How to use the voltmeter: Connect the red wire of the voltmeter to the V/Ω/Hz and the black
wire to the COM. Set the rotating knob to 20 Volts in the (V- ) section. Connect the other two
ends of the wires to the positive and negative terminals of the battery. (Red on positive and black
on negative). (Refer to the multimeter diagram below)
Record your reading in the data table.
b. Measure the voltage across each light bulb. The voltmeter should be
connected in parallel with the light bulb, as shown in the figure below. Record
your reading in the data table.
Connection diagram
Scientific diagram voltmeter connection
Measuring current in a series circuit:
c. Measure the current across each light bulb using the Ammeter.
How to use the Ammeter: Connect the red wire of the ammeter to the 20A MAX and the black
wire to the COM. Set the rotating knob to 2m in the (A-) section. The other two ends of the wires
should be connected to the circuit in series, as shown in the figure below.
Record your reading in the table below.
Connection diagram
Circuit type:
simple or series
Simple, 1 light
bulb
Scientific diagram
Observation of
brightness
Voltage reading
Light bulb 1:
Ammeter connection
Current reading
Series, 2 light
bulbs
Series, 3 light
bulbs
Light bulb 1:
Light bulb 2:
Light bulb 1:
Light bulb 2:
Light bulb 1:
Light bulb 2:
Light bulb 3:
Light bulb 1:
Light bulb 2:
Light bulb 3:
3. Add a third light bulb in series with the first two. Draw your circuit in the
space below and compare the brightness of the 3 bulbs to the one light bulb
in step 1 and 2 light bulbs in step 2. Record your observation in the data
table.
a. Measure the voltage across each light bulb following the steps above. Record
your reading in the data table.
b. Measure the current across each light bulb following the steps above. Record
your reading in the data table.
Parallel Circuits:
1. Connect 2 light bulbs in parallel. Draw your circuit in the space below and
compare the brightness of the 2 bulbs to the one light bulb in step 1 (simple
circuit. Record your observation in the data table.
Measuring voltage in a parallel circuit:
a. Using the voltmeter, measure the total voltage of the battery.
How to use the voltmeter: Connect the red wire of the voltmeter to the
V/Ω/Hz and the black wire to the COM. Set the rotating knob to 20 Volts in
the (V- ) section. Connect the other two ends of the wires to the positive and
negative terminals of the battery. (Red on positive and black on negative).
Record your reading in the table below.
b. Measure the voltage across each light bulb. The voltmeter should be
connected in parallel with the light bulb, as shown in the figure below. Record
your reading in the table below.
Scientific diagram
voltmeter connection
Measuring Current in a parallel circuit:
c. Measure the current across each light bulb using the Ammeter.
How to use the ammeter: Connect the red wire of the ammeter to the 20A
MAX and the black wire to the COM. Set the rotating knob to 2m in the (A-)
section. The other two ends of the wires should be connected to the circuit
in series, as shown in the figure below.
Record your reading in the table below.
Scientific diagram
Ammeter connection
2. Add a third light bulb in parallel with the first two. Draw your circuit in the
space below and compare the brightness of the 3 bulbs to the one light bulb
in step 1, and 2 light bulbs in step 2. Record your observation in the table
below.
d. Measure the voltage across each light bulb following the steps above. Record
your reading in the table below.
e. Measure the current across each light bulb following the steps above. Record
your reading in the table below.
Circuit type:
parallel
2 light bulbs
3 bulbs
Observation of
brightness
Voltage reading
Current reading
Light bulb 1:
Light bulb 2:
Light bulb 1:
Light bulb 2:
Light bulb 1:
Light bulb 2:
Light bulb 3:
Light bulb 1:
Light bulb 2:
Light bulb 3:
Conclusion:
Refer to your data table to answer questions 1 and 2 below:
1. How do voltage and current behave in a series circuit? Support your answer
by numbers (from data table).
2. How do voltage and current behave in a parallel circuit? Support your answer
by numbers (from data table).