1. Unit D - Electricity
Week 1

2. Static Electricity

3. I can…
Distinguish between static and current electricity, and identify examples of each

4. Static electricity Static electricity is a stationary electric charge
What does stationary mean?
The charge is not flowing like a current
Ex. Lightning, static electricity on clothing, “shocking people” by touching them, shock from your car.

5. Electrical charge
Remember that opposites attract which is true of negative charges
Most objects have an equal number of positive and negative charges so they are considered neutral
When an object has more of one charge we say it is charged
Ex. An object with extra electrons is negatively charged

6. Draw this picture in your Notes
Draw this picture in your Notes! Positive Charge = Protons Negative Charge = Electrons

7. Electrical discharge
Static electricity does not continue to flow, but it can undergo electrical discharge
The build up charge on an object can be attracted to another object and jump to that object
We call the spark an electrical discharge

8. Laws of electrical discharge
Opposite charges attract each other
Like charges repel each other

9. Charge separation
Charged objects cause a charge separation when they are brought close to neutral objects
For example, a negatively charged balloon, when brought close to a wall will cause the negative particles in the wall to be repelled, and therefore will be attracted to the positive particles left in the wall.

10. Review Questions
What is the difference between a proton and an electron?
What does it mean to be “statically charged”?
How do like charges interact?
How do unlike charges interact?
A neutral object contains no charge. Is this true?

11. Salt and Pepper Activity
Complete the Salt and Pepper Activity – This is due at the end of class.

12. Current electricity

13. I can…
Distinguish between static and current electricity, and identify examples of each
Identify electrical conductors and insulators, and compare the resistance of different materials to electric flow

14. Introduction https://www.youtube.com/watch?v=a3sviTa8hZw
Is the charge on the eel a static charge or a current?

15. Electrical Current
Static charges can discharge but they are not useful for operating electrical devices because they do not flow continually
The steady flow or charged particles is called electrical current
Electrical current can be used to run electrical devices as long as 2 things occur
Need a source of energy
Circuit must be closed

16. The necessary parts to a Circuit
1) Conductor- wire
2) Energy Source- battery or outlet
3) Load- the thing that uses the electricity
4) Control- often a switch

17. Conductor A conductor allows electricity to move through it easily
What are examples of conductors?
What is the opposite of a conductor? What are examples of these?

18. Insulators
in an insulator the electrons are bound tightly to the nuclei so they resist movement

19. Conductors and insulators
When would you want to use a conductor in a circuit?
When would you want to use an insulator in a circuit?

20. Conductor and Insulator Sort
Complete the Notebook Activity on Conductors and Insulators
What about wearing a Suit of Armor in a Lightning Storm?

21. Superconductors
Some metals are better conductors than others because they give less resistance to the electrons that are flowing
Superconductors are perfect conductors- they have no resistance to electron flow
Extremely low temperatures help reduce the resistance in the superconductors
What’s the issue to running a superconductor at a low temperature?

22. Circuits A circuit is a path that controls the flow of electricity
Usually electricity moves through solid wires but it can move through gases or other fluids
Open and Closed Circuits

23. Open and Closed Circuits
Complete the Smart Notebook Activity with Open and Closed Circuits

24. Quick Lab With a partner do the following lab– you have 20 minutes
1) Using any materials, make one light bulb light up
2) Using a battery, one bulb and 1 wire, make the light bulb light up
3) Using any materials, make 2 light bulbs light up
4) Make 2 light bulbs light up so that when you unhook one bulb, the other goes out
5) make 2 light bulbs light up so that when you unhook one bulb, the other stays on

25. Cells and batteries

26. I Can…
Investigate and evaluate the use of different chemicals, chemical concentrations and designs for electrical storage cells. (explain functions of parts and diagram)

27. Electrochemical Cells
An electrochemical cell is a package of 2 types of metals and an electrolyte
One metal has more free for electrons than the other metal, so when a wire is attached to create a circuit the electrons get to move from one metal to the next, which creates a current
There are 2 ends on a battery,
Cathode = positive
Anode = negative

28. Types of cells
Cells can power tiny pacemakers, toys, cars or computers
There are 2 types of cells
1) Dry cells- the electrolyte is a paste
2) Wet cells- uses a liquid electrolyte

29. Dry Cells
The electrolyte in a dry cell allows ions to flow which completes the circuit
An ion is an atom with a charge
Positive terminal- where electrons travel back to the cell
Negative terminal- where electrons travel from the cell

30. Dry Cells The 2 metals are called electrodes
One electrode becomes positively charged, and the other becomes negatively charged.
ALKALINE (having a basic electrolyte)- are some of the most common dry cells
What does alkaline mean again?

31. Wet cells
Wet cells often have a liquid such as sulfuric acid as their electrolyte
They are usually cheaper and easier to make than dry cells but are more dangerous
Vehicles use wet cells that need to be disposed of properly
There are individual cells that alternate within the battery
Each cell has a positive and a negative plate
The terminals in the battery are at the top
Think about it!
Is it correct to call a car battery a battery?

32. Wet Cell Batteries

33. Answer to Think about It!

34. Primary vs. Rechargeable cells
Primary cells: cells that can only be used one time
Rechargeable cells aka secondary cells- can be reused, the chemical reaction that occurred originally is forced to go back so it can be used again
Ni-Cd batteries are common secondary cells (made up of nickel and cadmium)

35. Battery Society today does not use the work battery correctly
A battery contains more than one cell

36. Electrochemistry
Alessandro Volta made the first practical battery around 1800 by stacking copper and zinc disks with an electrolyte solution
Other scientists used batteries to split molecules into their elements electrolysis (ex. Water used as a fuel for rockets by breaking into oxygen and hydrogen)
Electrochemistry was begun which is the study of chemical reactions involving electricity
Scientists discovered that by putting more than one cell together they could increase the current and the power of the battery

37. Electroplating
Electroplating uses the technology of a battery in reverse to create a layer of silver or gold on an object

38. How to electroplate
The metal that is to be coated is immersed in an electrolyte solution with metal bar in it.
The metal ions bond on the object and become a solid metal deposited on top of the less expensive materials

39. Controlling the flow of electrical current

40. I can…
Draw and troubleshoot circuit diagrams for a variety of specific purposes.
Explain how switches and resistors can control electrical flow, and predict the effects of these changes on output in a circuit.

41. A Unique circuit
Neon signs have neon gas in them, when electricity is run through them they glow.
The circuit needs to be complete and needs to be controlled carefully

42. Resistors
Resistance is a measure of how difficult it is for electrons to flow through a substance
A resistor uses power (a load can be a resistor)
Resistance is measured in ohms –symbol Ω (omega)
The more resistance a substance has the more energy it takes from the electrons that pass through it

43. Switches and Variable resistors
Switches allow the control of a circuit by simply shutting it “on” or “off”
A variable resistor or a rheostat can adjust the resistance in an object that the current flows through
Ex. Volume control on stereos, dimmer light switch

44. Analyzing and building electrical circuits

45. I Can…
Draw and troubleshoot circuit diagrams for a variety of specific purposes.
Explain how switches and resistors can control electrical flow, and predict the effects of these changes on output in a circuit.

46. Types of circuits
The most economical way to design a circuit is in a loop
However, we do not always want every part of the circuit being dependent on the others in the circuit
Ex. Would it be convenient for a plug-in to only work if the light switch was on?

47. Other types of Circuits
Series Circuits
Parallel Circuits

48. Series circuit
In a series circuit there is only one pathway for the current
If the pathway is interrupted the circuit cannot function
Problem: adding more things increases the total resistance  light bulb will get dimmer as we add more

49. Parallel circuit
Parallel circuits have a current path for each section of the current
A break in one pathway does not affect the others
Adding more pathways decreases the total resistance

50. Parallel vs Series
Complete the Smart Notebook Activity using Series and Parallel Circuits

51. Circuit drawing
We use special (easy to draw) symbols to represent parts in a diagram
An electrical diagram is called a schematic
4 parts of a circuit
Source
Conductor
Switch or control
Load

52. Lets draw parts for our Schematic Diagram

53. Tips for drawing schematics
Conductors are always drawn in straight lines with 90 degree angles
The symbols are made the same size
Conductor lines are not allowed to cross

54. Example

55. Complete the Circuit Assignment in your notes.
A closed circuit with a two-cell battery, a bulb and a switch.
An open circuit with a three-cell battery, a bulb and a switch.
A closed circuit with a three-cell battery, two bulbs, a switch and an voltmeter
A circuit with a two-cell battery and two bulbs that can are controlled by one switch.
A circuit with a three-cell battery and two bulbs, each of which are controlled independently by a switch.

56. Practice 1 Draw a schematic in a circuit made from: A battery
2 light bulbs
A switch
Conductors (Wires)

57. Practice 2 Draw a schematic diagram in a series including these things
Resistor
Switch
Voltmeter
Fuse
Battery made of 3 cells

58. Practice 3 Draw a schematic diagram in parallel with the following:
2 cells that power the whole circuit
A light turned on by one switch
2 more lights turned on by a switch together
A third switch that turns on or off all the lights together

59. Lets read!
As a class read about House Wiring and Microcircuits in your notes.
What is a transistor?
What is a microcircuit?

60. electrical safety

61. I can…
Assess the potential danger of electrical devices, by referring to voltage and current rating (amperage) of the devices, and distinguish between safe and unsafe activities.

62. Review What is the difference between static and current electricity?
What are some examples of conductors and insulators?
What four things do we need to have in a circuit?

63. Electricity moves through the path of least resistance– where it is the easiest to flow
A short circuit is a circuit where there isn’t any protection and the electricity moves quickly and can cause damage
The 3rd prong on a cord leads to the ground and is called a ground wire

64. The number of amps of a current is more important in terms of the danger of being shocked
Current from A to A will cause a painful shock and loss of muscles control
What does this mean for a person being shocked?
A current as low as 0.1 A can be fatal

65. The dangers of electrical shock
To protect yourself from electric shock you never want to allow electricity to run through you
Why are you safe in your car if a power line fell on it?
When are you not safe?

66. Factors affecting electrical shock
Different situations affect how bad an electrical shock is
One a dry day with running shoes on you may just feel a tingle from an electrical fence, but the same fence on a rainy day when you are barefoot could really hurt

67. Protecting yourself from Electrical Shock
Every plug in device in Canada must have a label on it showing what voltage it requires and what current it can use
The higher these numbers the more harm it can do

68. Plugs, Fuses and breakers
Fuse: contain a very thin piece of metal that will melt if too much current flows through it stopping the circuit
Need to be replaced (like in a car)
Breakers- they “ short out” when too much current is sent through them
Need to be cooled (like in your home)

69. Danger of lightning
A lightning strike can give a current up to A and it can kill
Lightning usually strikes at the highest point on a horizon
Lightning rods are connected to the ground through a wire to allow the discharge to dissipate to the ground

70. Demonstration Blow a Fuse! http://www.youtube.com/watch?v=ZT3HhDj8bRk