1. Lesson 2: What Makes a Circuit?
Unit 1
Lesson 2: What Makes a Circuit?

2. Objective: Series Circuit
By the end of this lesson you should be able to define a series circuit.

3. Comprehension: Series Circuit

4. Vocabulary: Series Circuit
Electric current – a flow of electric charges
Electric circuit – a continuous pathway that can carry an electric current
Series circuit – an electric circuit with only one path for current

5. Electric Current Electric current – a steady flow of electric charges
Current electricity is used to power most electrical things
It is easier to control than static electricity

6. Electric Current Electric currents can only move along paths
It is not random
It moves continuously, as long as there is a path to follow

7. Electric Circuit
Electric circuit – a continuous pathway that can carry an electric current
Pathways can be open or closed
Closed pathways provide usable energy

8. Electric Circuit
Circuits need a source to provide the movement of the electrical charges
A battery is an example
Two kinds of circuits: series and parallel

9. Series Circuit
Series Circuit – an electric circuit with only one path for current to flow through
An electric current must go all the way around for anything to work

10. Series Circuit: Travel of the electrical current
First the current leaves the power source
Then it travels through the wire
It passes through each attached device
Finally it ends up back in the power source
This pattern repeats as long as the pathway is closed

11. Series Circuit + + + Battery + - Shows a series circuit in action
- After a click, shows what happens when the series gets broken
Battery +

12. Series Circuit Is mostly used for simple devices
Flashlights, small lighted signs, bicycle flashers
If one part of a series does not work, the whole thing will not work
Everything attached to a series circuit is on when one thing is on

13. Series Circuit
The more devices attached to a series circuit, the less effective each device is
Which circuit will have the brightest lights? Why?

14. Series Circuit
Buddy share: Would it be a good idea to use a series circuit in a house? Why or why not?

15. Comprehension Closure
What is a series circuit?

16. Exploration: Series Circuit

17. Group Exploration: Making a Series Circuit
Your group will go to two different stations
You have a creation station as well as a writing station
You will have 10 minutes at each station
You will only rotate when the teacher tells you to

18. Exploration Closure: Series Circuit
Draw a picture of a series circuit. Label the different pieces in your picture.

19. Comprehension: Parallel Circuit

20. Objective: Parallel Circuit
By the end of this lesson you should be able to define a parallel circuit and tell the difference between a series and a parallel circuit.

21. Vocabulary: Parallel Circuit
Parallel circuit – an electric circuit with two or more paths for current
Resistance – how much a material opposes, or resists, the flow of electric current
Short circuit – a flaw in a circuit that allows a large current to flow through where it isn’t wanted

22. Check in…
Remember that a series circuit is a circuit where there is only one path for the energy to flow

23. Parallel Circuit
Parallel circuit – an electric circuit with two or more paths for current
If one path is blocked, the charges can use another path to continue moving
It gives the electrical charges options for movement

24. Parallel Circuit
You can put many different devices on a parallel circuit
The current is split between pathways
The current can go around an object not working
Houses and buildings are wired with parallel circuits
Adding another device does not change the capabilities of other devices

25. Parallel Circuit + + + + + Battery +
- Shows a parallel circuit in action
- After a click, shows what happens when the parallel gets interrupted
Battery +

26. Resistance
Resistance – how much a material opposes, or resists, the flow of electrical current
The greater the resistance, the less current can pass through
Smaller wire has greater resistance than thicker wire

27. Resistance
Which wire would be better to use? Why?

28. Resistance = Light
In a light bulb the light is actually the resistance of the electrical current
The filaments (thin wires) in the bulb has high resistance
First the filament gets hot, then it glows

29. Resistance = Light

30. Short Circuit
Short circuit – a flaw in a circuit that allows a large current to flow through where it isn’t wanted
A short circuit prevents the rest of a circuit from working

31. Short Circuit A safety device is a fuse
A fuse has something that melts if it gets too hot and breaks the circuit
This keeps damage from happening

32. Fuse
Has anyone ever plugged something in and it doesn’t work? Why might that be?

33. Comprehension Closure: Parallel Circuits
What is the difference between a series circuit and a parallel circuit?

34. Exploration: Parallel Circuit

35. Group Exploration: Making a Parallel Circuit
Your group will go to two different stations
You have a creation station as well as a writing station
You will have 10 minutes at each station
You will only rotate when the teacher tells you to

36. Exploration Closure: Parallel Circuits
Draw a picture of a parallel circuit. Label the different pieces in your picture.