Buggé: DC Circuits 1
Circuit Construction Kit
1.1 Observe and Find a Pattern
Open the program Circuit Construction Kit (http://phet.colorado.edu). Build the following circuits and describe
what you observe. First draw the picture the way it appears on your screen and record the outcome of the
experiment in words. Keep your diagrams organized and spaced out. Make sure you draw the connections for
the light bulb accurately.
a) One light bulb, one battery, two wires
Picture
Describe what you observe
b) One light bulb, one battery, one wire
Picture
Describe what you observe
Explain what you observe
using the energy approach
The energy of the battery is
transformed into the thermal
and light energy of the bulb.
Explain what you observe
using the energy approach
c) Summarize
a. What did you learn about connecting a light bulb in a circuit?
b. Where did the energy for the light bulb to glow come from?
Lesson activities adapted from ALG and PUM, Etkina and Van Heuvelen, 2010
Buggé: DC Circuits 1
1.2 Explain
a) Return to the circuit construction kit. Replace the light bulb with any element in the circuit and explain what
happens (do not hurt the dog) Try this with at least 5 elements:
Materials
Picture
Describe what you observe
Explain what you observe
using the energy approach
b)
For the experiment above, add a switch into at least 2 of your circuits.
Materials
Picture
Describe what you observe
**What is the purpose of the switch?
Lesson activities adapted from ALG and PUM, Etkina and Van Heuvelen, 2010
Explain what you observe
using the energy approach
Buggé: DC Circuits 1
c)
Set the battery on fire using the least amount of materials
Materials
Picture
Describe what you observe
Explain what you observe
using the energy approach
1.3 Explain Use your observations and explanations for the previous activities to answer the following
questions.
(a) Summarize the conditions that are necessary for the continuous flow of electric charge (called electric
current) through a metal wire.
(b) What properties of a given device are necessary to maintain a continuous electric current through circuit
element? Think of such a device in your everyday experience.
1.4 Design and Observe Draw pictures according to the word descriptions below. Build the circuits in the
PhET circuit construction kit, and observe the relative brightness of the light bulbs.
Circuit description
Draw a picture.
Discuss the brightness of
the light bulb (more bright
or less bright than in the
first experiment).
One 1.5-V battery, one lighted light
bulb, and wires.
Two 1.5-V batteries arranged so that
the positive side of one touches the
negative side of the other, forming a
chain (in physics they are said to be
in series), one lighted light bulb, and
wires
Two 1.5-V batteries are arranged so
that their positive sides are together
and negative sides are together,
forming a ladder (in parallel), one
lighted light bulb, and wires
1.5 Represent
Draw a picture of a circuit in which two light bulbs are connected in series. Then draw another picture when
they are connected in parallel. What is the same about those two pictures? What is different?
REFLECT What are the three most important things you learned about electric circuits
so far? How did you learn each? If you were the teacher, what questions would you ask to
find out if your classmates understood those three things?
Lesson activities adapted from ALG and PUM, Etkina and Van Heuvelen, 2010
Buggé: DC Circuits 1
Useful Definitions
Did you know?
Electric current: The electric current I through a wire in an electric circuit is the physical quantity equal to the
ratio of the electric charge ∆Q that passes a cross section in the wire and the time interval ∆t needed for the
charge to pass:
I = ∆Q / ∆t
In metal conductors the electric charge that flows is carried by free electrons (negatively charged particles).
Historically, the direction of the electric current was assigned as the direction that positive electric charges
moved. Thus, the direction of the electric current in an electric conductor is opposite the direction that the free
electrons move.
Here is an Idea!
Electric field accelerates electrically charged objects. Therefore there must be electric field present in the circuit
for the charged particles to flow in one direction. Think of what part of the circuit is responsible for this field.
For the conventional electric current (moving positive charge) to flow through a wire in the direction from 1 to
2, the potential of point 1 V1 should be higher then the potential of point 2 V2. Potential difference is
sometimes noted as voltage (ΔV). Positively charged objects flow in the direction of decreasing potential. Free
electrons move in the opposite direction – in the direction of increasing potential.
Did you know?
Series Circuit: A circuit whose devices are arranged so charge flows through each in turn. If one part of the
circuit stops the flow of charge, it will stop throughout the circuit.
Parallel Circuit: A circuit whose devices are connected to the same two points in the circuit. Any individual
device completes the circuit independent of the others.
Lesson activities adapted from ALG and PUM, Etkina and Van Heuvelen, 2010