Bell Ringer: Define to the best of your ability the definition of:

Transcription

1 Bell Ringer: Define to the best of your ability the definition of: Potential Energy Electric Potential Energy Electric Circuit Current Voltage Resistance Coulomb

2 Notes 7.1: Electrostatic Force This lesson brought to you by the shockingly Brilliant Mr. Jenkins!

3 Learning on Your Own: Active Physics Chapter 6, Section 1, Page 795 Static Electricity Active Physics Chapter 5, Section 2-4, Page Page 631 Physics (Red Book) Chapter 20, Page 540 Static Electricity; Chapter 22, Page 590 Current Electricity Chapter 23, Page 616 Series & Parallel Circuits Instructional Videos:

4 Lesson Objective: Produce electrically charged objects. Describe the behavior of like and unlike charged objects. Discover the factors that determine the force between electrically charged objects. Calculate the electrical force using Coulomb s Law. Implement the organizing principle of conservation of charge. Recognize the similarities between Coulomb s Law and Newton s Law of Universal Gravitation.

5 Vocabulary: Charge Electron Proton Neutron Coulomb (unit) Coulomb s Law Coulomb s Constant. Conservation of Charge Neutral Insulator Conductor

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9 Conductors and Insulators: Insulator: A material through which a charge will not move easily. Conductor: A material that allows charges to move about easily.

10 Electric Charge: Tell me what you know about electric charge? Similarly charged particles repel each other. Oppositely charged particle attract one another. At it s most fundamental nature, what is a charge? Well it is an intrinsic part of something. Just as mass is. Where does mass come from and where does charge come from are two fundamental questions of physics that have no been answered.

11 PHET Balloons and Static Electricity:

12 Demonstration: Take your one of your balloons, rub it on your head, and then try to stick it to the other balloon. What happens? Now, take the other balloon, rub it on your head, and then hold the two balloons close to each other. What happens? It the two balloons should push each other away. But they never touch one another so how does that work? How do they exert a force on one another without ever touching one another?

13 Electric Field:

14 Electric Field: Essentially, we can think of an electric field as the range that an electric charge q is capable of exerting a force. Much like the Sun and the planets, the further away an object is away from a charge, the less force that the charge is able to exert on the object.

15 Electric Force:

16 Electric Force:

17 Coulomb s Law: An electrostatic force acts between two charged objects. This electrostatic force depends on distance. It depends on the charge of each object in contact. SI Unit for Charge q: The coulomb C

18 Coulomb s Law: The force between two charges is equal to Coulomb s constant, time the product of the two charges, divided by the square of the distance between them. F = K q 1q 2 r 2 F = Electrostatic Force K = Coulomb s Constant = 9.0 x 10 9 N m/c 2 q = the amount of charge of the individual particle r = the distance between the two charges

19 Example:

20 Recap: There are two kinds of electric charges; positive and negative. Charges exert forces on other charges at a distance. The force is stronger when the charges are closer together. Like charges repel; opposite charge attract.

21 Higher Order Questions: 1. A distance of 1.0 meter separates the centers of two small charged spheres. The spheres exert gravitational force F g and electrostatic force F e on each other. If the distance between the spheres centers is increased to 3.0 meters, compare the gravitational force and electrostatic force between them.

22 Higher Order Questions: 2. State the similarities and differences between Coulomb s Law and Newton s Universal Law of Gravitation. 3. How does the electrical force vary with distance between two charges? Relate this numerically. 4. Explain what it means to be positively or negatively charged? 5. An object has an overall positive charge. Does this mean extra positive charges were added to this object? Explain your answer.