1. Electricity

2. Static Electricity
Two types of charged particles, positive (protons) and negative (electrons) exist
Positive charges are fixed and negative charges are free to move
A neutral object has the same number of positive and negative charges

3. A negative object has an excess of negative charge
A negative object has an excess of negative charge. A positive object has a deficit of negative charge.
Charges that are like repel, and charges which are unlike attract.
A neutral object is attracted to both the positive and the negative charges

4. Reminder – Atomic Structure
Draw an atom!

5. Important Points Number of protons Number of electrons
Number of Neutrons
This atom is neutral

6. The movement (transfer) of electrons from one atom to another changes the charge on the atom. When an atom loses electrons, the atom becomes positively charged. When an atom gains electrons, the atoms becomes negatively charged

7. Types of Charges
Electrostatic charge can either be positive or negative. Objects can also be neutral. We say there are three states than an object can have:
Neutral = the positive and negative charges on the object are balanced
Positively charged = more positive charges on the object than negative
Negatively charged = more negative charges than positive on the object

8. Showing Charges A neutral object.
I know this object is neutral because

9. Showing Charges A positively charged object.
I know this object is positive because

10. Showing Charges A negatively charged object.
I know this object is negative because

11. A neutral object (box one) that has become negatively charged (box two)
In both of the boxes, the number of _________________ has to be the same. The number of electrons is ______________ than the number of protons in box 2.

12. A neutral object (box one) that has become positively charged (box two)
In both of the boxes, the number of _________________ has to be the same. The number of electrons is ______________ than the number of protons in box 2.

13. Insulators and Conductors
Material are also identified based on how well they transmit electric charge.
Conductors - material allows the electric charge to easily pass through
Metals generally are conductors, but some are better than others. Good electrical conductors are copper, silver, and aluminum.
Electrons can move throughout the material

15. Insulators - does not easily allow the electric charge to pass through.
Insulators are generally non-metals. Some good insulators are rubber, most plastics, and glass
Electrons will not move easily within the material – therefore you can have a charge on one part of a insulator, but not another.

16. Questions….

17. Bill nye static video

19. How do objects become charged?
Friction, Conduction, Induction

20. How do objects become charged?
Friction
Some materials (wool, vinyl, glass) contain negative particles that are loosely held and are able to give away these charged particles. When this happens, these materials become positively charged, and the object they come in contact with become negatively charged.
When a charge moves onto an insulator (glass, rubber, plastic, etc.) the charge does NOT move – it is static. It stays in the same place.
When this happens, the charge can build up

21. Example: rubbing a balloon

22. The number of positive charges does NOT change, as they cannot move
***The number of positive charges does NOT change, as they cannot move. Only electrons move***
Practice: Draw what the charges would look like on the following objects. Positive charges on the first two have been provided for you.

23. A neutral square of glass
A neutral piece of cotton
After friction occurs, cotton gains electrons
Charge   
Glass: _________
Cotton: _________ + + + + + +

24. Notes about friction: Involves 2 objects being in contact
1 object will lose electrons
1 object will gain electrons
Both will start neutral, but in the end one object will be negatively charged, and one object will be positively charged

25. Static discharge – when the electrons move to balance out (shock, spark, lightening, etc.) This is a movement of electrons from one object to another – electrons repel each other and will move to even out amongst the objects that are close together.

27. Grounding – an object is said to be grounded if it is contact with the Earth. Electrons can be sent to the Earth to prevent them from building up in an object, IF that object is in contact with the ground.
A lightening rod acts to ground a building – if lightening (electrons) hit the rod, the electrons are transferred into the ground, not to the building itself.
This results in objects that are charged (either positive or negative) to become neutral

28. John Travoltage

29. Friction Electrostatic Series
How do I know which object will gain electrons, and which object with lose electrons?
Not all objects are able to ‘hold onto’ their electrons as strongly as others. The electrostatic series (see below) shows you which materials are able to hold onto their electrons, and which ones can’t.

30. Strong Hold on Electrons
Material
Weak Hold on Electrons
   
Strong Hold on Electrons
Acetate
Glass
Wool
Cat’s fur/Human hair
Calcium, Magnesium, Lead
Silk
Aluminum, Zinc
Cotton
Paraffin Wax
Ebonite
Polyethylene (plastic)
Carbon, Copper, Nickel
Rubber
Sulfur
Platinum, Gold
Electrostatic Series
Example: Acetate has a weak hold on its electrons. It will easily lose electrons if it is rubbed with any of the other materials in the list.
Increasing Tendency to Gain Electrons

31. Circle the object that will LOSE electrons
Glass and Rubber Plastic and Nickel
Sulfur and Silk Calcium and Wax
Cotton and Plastic Silk and Glass
Gold and Ebonite Acetate and Cotton
Fur and Carbon Hair and Copper

32. 2. Write on the lines which of the 2 materials will be NEGATIVE after friction occurs
Silk and Ebonite ___________
Sulfur and Rubber ___________
Aluminum and Glass ___________
Magnesium and Platinum ___________

33. 3. Write on the lines which of the 2 materials will be POSITIVE after friction occurs
Cotton and Wool ___________
Plastic and Rubber ___________
Nickel and Lead ___________
Silk and Plastic ___________

34. Charged by Friction Worksheet

35. Charging by Conduction
Electric charge can travel from one object to another by touching a charged object to another (usually neutral) object. (Friction is not involved)

36. Charge moves between the charged object and the neutral object
Transfer of electrons occurs until the negative particles repel each other with equal force on both objects
Touching a negatively charged object to a neutral object - Once negative particles transfer has stopped, there are excess negative particles on both objects
Touching a positively charged object to a neutral object – once negative particle transfer has stopped, there is a deficiency of negative particles on both objects

40. What do you notice about the new charge on the neutral object and the charged object that it has come into contact with?

41. Transfer of electrons – when electrons are rapidly transferred from one object to another
A shock or spark
Lightening
Often objects don’t have to completely touch for a discharge to occur – electrons will ‘jump’ through the air
Occurs when there is an imbalance of charges between two objects.
Will NOT occur if both objects have the same charge (because there will be no transfer or electrons between the two objects)

42. Example: Touching a doorknob
Example: Touching a doorknob. You may have developed a negative charge by walking across a carpeted floor (friction). When you get close to a doorknob the electrons will ‘jump’ to the doorknob, giving a shock.

43. Practice with Conduction
Draw an arrow in the box to show the direction that electrons will move when the two objects touch.
Draw the charges (both positive and negative) that would end up on each object after contact is made.
On the lines below, indicate whether each object is positive, negative or neutral.

46. Fill in the chart by writing the text from each box into the appropriate spot in the table

48. Charging by Induction
Another way to cause an object to become charged is through the process of induction. Unlike friction and conduction, objects do not have to touch for this process to occur. It can either be permanent, or temporary

49. Induced Charge Separation – when an object becomes TEMPORARILY charged by being close to a charged object.

50. *****If the balloon is removed from the wall, the wall will no longer be charged as the electrons will be able to freely move around again.*****
PHET simulator

51. Charging by Induction - Permanent
An induced charge CAN become permanent when using a conductor
This occurs through a process called grounding
Grounding is a way to discharge an object. This means to remove the excess charge on an object.

52. Here is another example of an INDUCED charge
Here is another example of an INDUCED charge. (See the negative and positive ends?)
If the copper tube is then grounded, the electrons on the right end will be able to escape the copper tube. Remember, like charges repel each other. These electrons are being forced into a small area, and WANT to be separated (spread further apart).

53. Grounding the copper tube using your finger: Touching the rod allows the electrons to flow through you to the ground. The straw must still be near the rod for this to occur.

54. Once the charged plastic straw has been removed, a permanent positive charge is left on the copper tube. Notice that the permanent induced charge is opposite to the charge on the plastic straw.
Other ways to ground something: attach a wire to the ground, or connect a wire to a water tap or pipe

55. Example 2:
A negatively charged rod comes near a neutral metal sphere which is grounded
A charge separation occurs

56. Example 2:
Electrons leave the metal sphere through the grounding wire (notice the symbol)
The metal rod is removed. What is the charge left on the metal sphere?

57. Example 3: Permanent charge by induction
Two neutral copper rods are touching as shown in the diagram. A negatively charged straw is brought nearby the left copper tube. With the charged rod nearby, the copper tubes are separated.

58. The charge remaining on the copper tubes after they are separated is shown the diagram below. As above, the straw must remain in place until AFTER the rods have been separated.

59. THINK ABOUT IT: Why does the straw have to stay in place until AFTER the copper tube is grounded or separated as in the example above?

60. Put the text from the boxes below into the chart in the correct spot