1. Static Electricity

2. Yesterday…
Static electricity is when a charge remains on the surface of an object
Positively Charged / Negatively Charged
Law of Electric Charges
Charging by Friction

3. Learning Goals Today we will learn... Two methods of charging objects
Amount of charge
Strength + Size of Electric Fields
What are grounds and how do they work?

4. Investigating charge
With the following hand-out investigate two ways to charge an object. Think about: What is happening to the electrons? What are the net charges of each material? How does this relate to the Law of Electric Charge?

5. Charging by induction Temporary Positive Charge Neutral Ball
Return to neutral state
Negatively Charged Rod
Think about: Is there a way to make this charge permanent?

6. CHARGING BY CONTACT
Neutral ball
Movement of electrons
Negatively charged ball
Negatively charged rod
An object that is charged by contact will always get the same charge as the object that charges it

7. AMOUNT OF CHARGE
NET CHARGE: The difference between the number of protons and electrons contained
12 protons + 12 electrons
If two electrons are lost … what is the net charge?
ELECTRIC FORCE: Attraction that pulls objects together, repulsion that pushes objects apart

8. ELECTRIC FIELDS
Explains how a charged object can exert force on another object without touching it
The space around a charged object
The larger the net charge the stronger the electric field
The further from the charged object, the weaker the electric field
Electric forces transmitted at the speed of light
Speed of light = 299 792 458 m / s

9. How do you remove a static charge?
Ground: has a large number of charges. Can supply or remove electrons as needed. Grounds remain neutral at all times.
Grounding: when the conductor is connected to the earth, allowing free flow of electrons

10. Overview Today we learned…
How charging by induction and charging by contact occurs
What the “amount of charge” is
About electric fields and electric force
How to remove charges using grounds

11. Exit Card
Using what we learned today …
How could you make this ‘induced charge’ permanent instead of temporary?

12. Homework
Textbook Questions: Page 417: 1-3, 5, 6, 8