Why electric charges move?

1. Why electric charges move?

2. 1-21 • Construct a double bubble map comparing and contrasting what you know about electricity and magnetism. • Create a picture of an atom and include the charges.

3. 32.1Electrical Forces and Charges The helium nucleus is composed of two protons and two neutrons. The positively charged protons attract two negative electrons. Electrical forces arise from particles in atoms. The protons in the nucleus attract the electrons and hold them in orbit. Electrons are attracted to protons, but electrons repel other electrons.

4. 32.1Electrical Forces and Charges (preassessment 1) The fundamental rule at the base of all electrical phenomena is that like charges repel and opposite charges attract. Opposites attract and likes repel

5. 32.2Conservation of Charge (preassessment #2) Principle of Conservation of Charge Electrons are neither created nor destroyed but are simply transferred from one material to another. This principle is known as conservation of charge. In every event, whether large-scale or at the atomic and nuclear level, the principle of conservation of chargeapplies.

6. Why does the balloon pick up paper but the pipe does not?

7. Conductor – material that has atoms that hold electrons loosely so they can flow • Insulator – material that holds electrons tightly so they are unable to flow

8. What is the difference between an insulator and a conductor? • What would affect how the charges move on the Hockey simulation?

9. 1/22 • What is the difference between an insulator and a conductor? • If you were in a car that got struck by lightning what would you do?

10. 5. Whether a substance is classified as a conductor or an insulator depends on _____ • a. how soft the substance is. • b. how fast electrons move. • c. how thick the substance is. • d. how tightly the atoms hold their electrons.

11. 6. A battery is connected to a light bulb with copper wire to complete a circuit. The bulb lights immediately. Which of the following best describes why the bulb lights? ______ • a. The battery supplies electrons, which move through the bulb but not the wire. • b. The battery supplies chemicals, which pass through the bulb to the end of the wire. • c. The battery supplies heat energy, which causes the bulb to produce light energy. • d. The battery supplies voltage, which causes the electrons throughout the circuit to move.

12. What makes the charge move? • Electrostatic force – push or pull caused by electric field

13. 32.1Electrical Forces and Charges The enormous attractive and repulsive electrical forces between the charges in Earth and the charges in your body balance out, leaving the relatively weaker force of gravity, which only attracts.

14. Vectors – arrows present both magnitude and direction

15. 33.1Electric Fields An electric field is a force field that surrounds an electric charge or group of charges. A gravitational force holds a satellite in orbit about a planet, and an electrical force holds an electron in orbit about a proton.

16. Phet conductor simulation • http://phet.colorado.edu/en/simulation/conductivity

17. 1/24 • 1. Do you think it is better for students to take biology in 9th grade (physics in 11th) or physics in 9th grade (biology in 11th) Why? • What is the fundamental rule of electrostatics? • Vocab: • Vector = arrow that shows magnitude and direction • Computer lab Google : “ Phet electric field hockey”

18. 32.1Electrical Forces and Charges The enormous attractive and repulsive electrical forces between the charges in Earth and the charges in your body balance out, leaving the relatively weaker force of gravity, which only attracts.

19. 33.1Electric Fields • The direction of an electric field at any point, by convention, is the direction of the electrical force on a small positive test charge. • If the charge that sets up the field is positive, the field points away from that charge. • If the charge that sets up the field is negative, the field points toward that charge.

21. 1/29 How will the electrostatics force change if the charge is doubled on one of the objects? • If an electron at a certain distance from a charged particle is attracted with a certain force, how will the force compare at 2 times this distance?

22. 32.3Coulomb’s Law For charged objects, the force between the charges varies directly as the product of the charges and inversely as the square of the distance between them. Where: d is the distance between the charged particles. q1 represents the quantity of charge of one particle. q2 is the quantity of charge of the other particle. k is the proportionality constant. The symbol k is a proportionality constant known as the Coulomb's law constant. The value of this constant is dependent upon the medium that the charged objects are immersed in. In the case of air, the value is approximately 9.0 x 109 N • m2 / C2.

23. An electric field is a storehouse of energy.

24. Electrical potential – the amount of potential energy per charge (Volts) • Electrical potential energy – the amount of energy a charge has due to its location

25. 33.4Electrical Potential Energy To push a positive test charge closer to a positively charged sphere, we will expend energy to overcome electrical repulsion. Work is done in pushing the charge against the electric field. This work is equal to the energy gained by the charge. The energy a charge has due to its location in an electric field is called electrical potential energy. If the charge is released, it will accelerate away from the sphere and electrical potential energy transforms into kinetic energy.

26. 33.5Electric Potential Electric potential is not the same as electrical potential energy. Electric potential is electrical potential energy per charge.

27. 9/4 • Use the formula for coloumb’s law from yesterday. Two charges of 2 are a distance of 1 meter apart. What is the electrostatic force between them? • What is the electrostatic force between them if they are moved to 2 meters apart? • If an electron at a certain distance from a charged particle is attracted with a certain force, how will the force compare at 2 times this distance?

29. 33.2Electric Field Lines • You can use electric field lines to represent an electric field. • Where the lines are farther apart, the field is weaker. • For an isolated charge, the lines extend to infinity. • For two or more opposite charges, the lines emanate from a positive charge and terminate on a negative charge. • Video • http://www.learner.org/resources/series42.html?pop=yes&pid=557# • #29 at about 7:45

31. 1/30 c a • The  figure  shows  the  path  of  a  positive  charge  moving  from  left  to  right  due  to  charges  A  and  B and c    What  are  the  charges  on  A , B and C? • What is the difference between electric potental and electric potential energy? b

32. Assignment Problem asked “How does the electric fields and charges affect your ability to make a goal in electric field hockey”? How is the movement of the puck affected the strength of the electric field. Use claim, evidence (give examples), and reasoning to support your answer Using vocabulary in reasoning. Attract, repel, charge, positive negative, electric potential energy, electrical field