1. Electricity Static Rub balloon on long hair girl
Ask Why does hair stand out
(force of repulsion) (charging by friction) (electron affinity)
Stick balloon to wall
Ask why does it stick
Induced (Temporary) charge separation
Shocks from seats. Clothes from dryer. Blankets showing sparks. Why
Show simulation charging balloon and sticking to wall. Electric discharge
Show charging by conduction and induction with the good electroscope after they try in the lab
The text is incorrect on p603 when it talks about charging by induction. They are describing induced charge separation

4. Electricity
Do your clothes stick together when you take them out of the dryer?
Have your clothes ever made crackling noises when you took them off?
Have you ever gotten an electric shock from another person?
Have you ever seen sparks in your blanket at night?
Ask these questions and expect to get replies but don’t let it go on too long.
Be encouraging if someone says something daft try and be positive.

5. Has this happened to you?

6. Why ??? Static Electricity
Static electricity occurs when there is a build up of electric charge on the surface of a material.
It is called static electricity because the charges don’t move (much).

7. Static Electricity Ben Franklin (and others)
Two types of electric charge
Plus and Minus names
Like repel
unlike attract
Yes the kite is real

8. How do objects acquire charge?
Static Electricity
How do objects acquire charge?
Charging by friction
Induced charge separation
Temporary
Charging by contact
Charging by induction

9. Charging by Friction When a balloon rubs a piece of wool... + –
electrons are pulled from the wool to the balloon. + – –
Rubber has a higher electron affinity than wool
wool
The balloon becomes negatively charged and the wool positively charged

11. Induced Charge Separation
After being rubbed, a plastic ruler can attract small bits of paper.
WHY ???

12. Induced Charge Separation
when a charged rod is close to paper scraps...
Electrons are repelled. -
The attraction between the rod and + charge is greater than the repulsion between the rod and - charge.
attraction + –
paper
repulsion

13. Charging by Conduction

14. Excerpt From an Electric Novel
Carol put the gas pump nozzle on automatic and re-entered her car to write a check. Just then her daughter, wearing a wool sweater and nylon jacket and who's hair was standing out, reached out the window for the nozzle. Flames suddenly ignited her clothing.

15. Grounding This is called What Happened?
When you touch a positively charged metal ball electrons flow from the earth to the metal ball, neutralizing the charges. + + +
This is called + + –
Grounding

16. Charging by Induction
Bring a negatively charged rod near an object to produce induced charge separation -
induced charges + -
metal can

17. Charging By Induction
Bring a charged rod near an object to produce induced charge separation

18. Charging By Induction
Ground the object. Allowing electrons to flow

19. Charging By Induction
Remove the ground, then remove the rod.

20. A force must be pushing the hair apart

21. Static Electricity
Coulomb Experiment

22. Static Electricity Force (F) is in newtons (N)
Charge (Q) is in coulombs (C)
Distance (R) is in meters (m)
Coulomb Constant (k) 9 X 109 Nm2/C2

23. Static Electricity
You and your lab partner each have a net charge of one coulomb of excess positive charge and are about one meter apart. What is the force between you? (You weigh about 500N)

24. Static Electricity
How does one charge exert a force on a second charge when they do not touch?
Electric Field

25. Small charged grass seeds in oil between two charges.

26. Current Electricity Current electricity is the rate of flow of charge.
Current (I) Ampere (A) or (C/s)
Electrons in metals
Protons, Electrons or ions in liquids and gasses
AC / DC

27. Current Electricity Conductors – Insulators
Resistance (R): A material’s opposition to the flow of charges
Ohms (Ω)
Thickness, length, temperature (for metal wires)

28. Current Electricity
Electric Potential Difference (V): The difference in the amount of energy that a charge has between two spots in an electric field
J / C or Volt (V)
Gravity potential energy
battery

29. Electricity
Ohm: Was able to Relate current, resistance and potential difference for a circuit.
V = IR
Read 20.2

30. Electric Circuits
Electric Circuit: a completed (closed) path that allows electricity to flow
Circuit diagram: Uses symbols to represent the parts of an electric circuit

32. Electricity
Series Circuit
One path
I is constant
V adds
R adds

33. Electricity Parallel Circuit More than One path (branches)
V is constant
I adds
R goes down

34. Electricity Power: how quickly the energy is transferred
P = energy / time J/s watts W
P = VI

35. Electricity
Safety
Fuse
Circuit breaker
Gfi
Read 20.3

36. 4. Batteries are e¯ pumps.
a. They provide a voltage difference to a circuit.
b. Types: wet-cells & dry-cells