Lights, Sound, Action!
- 3 D-cell batteries
2 flashlight bulbs (at least 3 volt)
5 pieces of insulated copper wire 12-15 cm (5-6 inches
2 bulb holders
motor and fan blade
4 alligator clips
Doing the Activity
From your materials take a battery,
light bulb, and bulb holder, and two pieces of copper
wire. Make sure that 1.5 cm (1/2 inch) of insulation has
been stripped from each end of the wires so that you can
make the connections.
Carefully screw the bulb into the
holder. Connect one end of each wire to each of the two
clips on the bulb holder.
Connect the loose ends of one wire to
the battery. (Use tape to hold the wires in place, if
needed.) When the bulb lights, the path you have made
with your connections is called a complete, or closed
Each group now needs two batteries, two
bulbs, two bulb holders and four wires. Try to make two
bulbs light at the same time. When you wire a circuit so
that electricity flows first through one bulb and then
through the second, you get a series circuit.
- Follow this diagram. When each bulb has a separate
circuit, we say the circuit is a parallel circuit. You
have given each bulb its own circuit.
Talking it over
- To light the bulb, does it matter which direction the
positive or negative end of the battery is pointing?
- Observe what happens when you unscrew one bulb in a
series circuit. Why did that happen?
- When you used two or more bulbs in your series
circuit, did the additional bulbs burn as brightly as in
the circuit made with just one bulb? Did all the bulbs in
your series circuit glow with the same brightness? Why or
- If our homes were wired in series, what would happen
as we turn on more and more lights and appliances?
- When you use a parallel circuit, do all bulbs burn
with the same brightness? Are they brighter or dimmer
than they were in your series circuit? Why?
- Suppose you had a string of patio or Christmas tree
lights plugged in and one bulb burned out. What would
happen to the other bulbs if your lights were wired in
series? In parallel? Which kind of wiring for the lights
do you think would be better to use? Why?
- Name at least one advantage and one disadvantage of
electrical wiring done in parallel and done in
- What's Happening
- Electricity is a form of energy that comes from the
movement of electrons. Electrons are tiny
particles in any atom. Since electrons are
negatively charged particles, they are attracted to
positively charged objects and are repelled by negatively
charged objects, including other electrons. Movement of
electrons creates an electrical current. The
unbroken path or loop through which electricity flows is
called a complete or closed circuit. If the
electricity does not flow at all, then we know there is a
break in the circuit, or an open circuit. What
happens to the circuit when you turn off a light
switch? When you turn on a switch, the break is closed
and the electric current can now travel through the wire
to a light a bulb, buzzer a buzzer, or turn a fan.
Circuits can be wired in a series or in parallel. In
series wiring, there is only one path for the
electrons to follow. In a circuit made from batteries,
wires, and more than one bulb, the electrons must travel
through all the bulbs to complete the circuit. In
parallel wiring, the electrons have more than one
path in which they can travel. Now when one bulb is
disconnected, other paths are still unbroken.
- More Challenges
- Make a circuit that produces light, sound, and motion
all at once! Is it wired in series or in parallel?
- Activity Source
- "Funtivities: Hands-on Science and Math." Iowa State
University Program for Women in Science and Engineering.
Extension Distribution Center
(515) 294-5247, order # 4H-952 for grades 4-5, #4H-952LDR
for grades 4-5 leader's guide, #4H-953 for grades 6-8,
#4H-953LDR for grades 6-8 leader's guide.