1. ELECTRICAL CIRCUITS

2. What is an ELECTRIC CURRENT? 4. Explain what a CLOSED CIRUCIT is?
PRE-TEST QUESTIONS
What is a Circuit?
What is an ELECTRIC CURRENT?
3. What are the THREE conditions that must be met for an electric current to flow?
4. Explain what a CLOSED CIRUCIT is?
5. DLE at least 3 configurations to light a bulb with just the materials from the
“LIGHT IT UP” activity.

3. ELECTRICAL CURRENT
You cannot see electricity because electrons, the charged particles whose movement through a substance creates electricity, are too small to be seen even with a microscope.
When electrons flow through certain substances (like copper wire), they form an electrical current.
Electrical currents provides energy to power all kinds of things, from video games to refrigerators to cars!

4. CELL-POWER SOURCE (BATTERY) In which direction does the current flow?
ELECTRICAL CURRENT
An ELECTRICAL CURRENT is the flow of electrons through a conductor is called electrical current.
CELL-POWER SOURCE (BATTERY)
Electron - +
In which direction does the current flow?
From the Negative terminal to the Positive terminal of a cell (battery).

5. electric current to flow, THREE CONDITIONS must be met.
In order for
electric current to flow,
THREE CONDITIONS must be met.

6. Such substances, called
FIRST CONDITION:
One is presence of a substance that allows electrons to move, or flow, easily through it.
Such substances, called
CONDUCTORS!

7. A conductor is a material
The CONDUCTOR
A conductor is a material
(usually a metal such as copper) that allows electric current to pass easily.
The current is made up of electrons. This is opposed to an insulator which prevents the flow of electricity through it hold onto their electrons
more strongly.

8. 2. The second requirement is the presence of a power source.
SECOND CONDITION:
2. The second requirement
is the presence of a power source.
Whatever its form, a source of electric current creates what is called a voltage difference, which pushes electrons through the circuit.
The chemical reactions inside batteries produce voltage differences between one end of the cell and the other that result in electric current.

9. THE CELL (BATTERIES) The cell stores chemical energy and
transfers it to electrical energy when
a circuit is connected.

10. This is a length of conducting material
THIRD CONDITION:
3. Lastly, electric current requires
a closed circuit.
This is a length of conducting material
(like a wire) connected at each end to a power source (like a battery) passing through the "load”,(like a light bulb) or the object that needs the current to operate.

11. THIRD CONDITION: The circuit allows a direct,
uninterrupted flow of electrons from the power source and back –
a complete circular connection with
no beginning or end.
CONDUCTING MATERIAL
THE “LOAD”
CLOSED
CIRCUIT
POWER SOURCE

12. CIRCUIT
The word circuit comes from the Latin circuitus, which means "to go around”. A circuit is a path for electrons to flow around. Think of it as a circle. The paths may split off here and there but they always form a line from the negative to positive.

13. ACTING A CIRCUIT Act out an electric circuit, as follows:
Students will join the teacher in forming a circle.
The teacher will represent a battery and the students will represent a wire conductor The circle represents a circuit.
STUDENTS
(wire conductor)
TEACHER
(Battery)

14. ACTING A CIRCUIT
2. Distribute a ball to each member of the circle, including the teacher. These balls represent electrons inside a wire conductor. Remember, a wire conductor is full of electrons.
BALLS
(ELECTRONS)

15. ACTING A CIRCUIT
Remember, your teacher is playing the part of the battery in this circuit. ALL batteries have a positive end, represented by the left hand, and a negative end, represented by the right hand.
Right Hand
NEGATIVE END
(-)
Left Hand
POSITIVE END
( )

16. ACTING A CIRCUIT
3. The Teacher will pass an "electron" to the student on their right. The student receiving the teacher’s electron should in turn pass the one he or she is holding to the right. 4. Students continue passing on electrons to the person to their right. Now because electrons share the same negative charge, they repel one another, which keeps them moving along in the same direction.

17. ACTING A CIRCUIT
4. Remember, as long as the circle remains intact and the electrons continue to flow, their circuit is closed. 5. To illustrate what happens when a circuit breaks, or opens, create a gap in the circle of students that is too wide across to pass electrons. The current will stop as a result.

18. The “LOAD” ELECTRON moving From the POSITIVE POWER SOURCE (CELL)
moving to the
NEGATIVE

19. REMEMBER…. CLOSED NOT CLOSED Electricity will only
flow in a CLOSED circuit.
Electricity will not flow
if the circuit is NOT CLOSED.
CLOSED
NOT CLOSED

20. SIMPLE CIRCUITS
Here is a simple electric circuit. It has a cell, a lamp, and a switch.
wires
cell
lamp
switch
To make the circuit, these components are connected together with metal connecting wires.

21. If there were any breaks in the circuit, the current could not flow.
SIMPLE CIRCUITS
When the switch is closed, the lamp lights up. This is because there is a continuous path of metal for the electric current to flow around.
wires
cell
lamp
switch
If there were any breaks in the circuit, the current could not flow.

22. Scientists usually draw electric circuits using symbols;
CIRCUIT DIAGRAM
Scientists usually draw electric circuits using symbols;
cell
lamp
switch
wires

23. There are two types of electrical circuits;
Types of CIRCUITS
There are two types of electrical circuits;
SERIES CIRCUITS
PARALLEL CIRCUITS

24. SERIES CIRCUITS
The components are connected end-to-end, one after the other.
They make a simple loop for the current to flow round.
If one bulb ‘blows’ it breaks the whole circuit and all the bulbs go out.

25. PARALLEL CIRCUITS The components are connected side by side.
The current has a choice of routes.
If one bulb ‘blows’ there is still be a complete circuit to the other bulb so it stays alight.

26. Probably the most important thing to remember is understanding that a circuit must be complete.
In other words provide a path that allows electricity to circulate from one pole of the battery, along a wire, through the elements of the circuit, along the wire again and back to the other pole.
This is completing the circuit, and without this there is no flow of electricity.

27. What Kind of Circuit Is this?

28. PARALLEL
(with 3 “LOADS”)!

29. LIGHT IT UP! MATERIALS: 1.wire strippers 2. insulated wire
(about 6 inches long)
3. Small flashlight bulbs
4. Fresh D-cell batteries
5. Tape (masking or electrical)

30. (teacher should do this ahead of time).
LIGHT IT UP!
Each pair of students will need two pieces of insulated wire, a battery, a flashlight bulb, and tape.
Cut the insulated wire into six-inch segments. Remove one-half inch of plastic insulation off the ends of each segment. To do this, you can use wire strippers or you can score the plastic insulation around the wire with sharp scissors and then carefully but firmly pull it off with your fingers
(teacher should do this ahead of time).

31. LIGHT IT UP!
3. Next, students are going to apply what they just learned about circuits to light a bulb.
In teams of two, distribute two lengths of wire (with the ends stripped), a flashlight bulb, a D-cell battery, and some tape to each team.
Challenge: Students are to use their critical thinking skills and trial and error to get their bulbs to light.
Then they are to draw a diagram (DLE) of their circuit, making sure to include all its parts.

32. LIGHT IT UP!