Preview

1. Chapter 16 Section 1 Electric Charge Preview • Statics • Circuits • Electricity and Magnetism

2. Chapter 16 Section 1 Electric Charge Objectives • Understandthe basic properties of electric charge. • Differentiatebetween conductors and insulators. • Distinguishbetween charging by contact, charging by induction, and charging by polarization.

3. Chapter 16 Section 1 Electric Charge Properties of Electric Charge • There are two kinds of electric charge. • like charges repel • unlike charges attract • Electric charge is conserved. • Positively charged particles are calledprotons. • Uncharged particles are calledneutrons. • Negatively charged particles are calledelectrons.

4. Chapter 16 Section 1 Electric Charge Electric Charge Click below to watch the Visual Concept. Visual Concept

5. Chapter 16 Section 1 Electric Charge Properties of Electric Charge, continued • Electric charge is quantized.That is, when an object is charged, its charge is always a multiple of afundamental unit of charge. • Charge is measured in coulombs (C). • The fundamental unit of charge, e, is the magnitude of the charge of a single electron or proton. e = 1.602 176 x 10–19 C

6. Chapter 16 Section 1 Electric Charge The Milikan Experiment

7. Chapter 16 Section 1 Electric Charge Transfer of Electric Charge, continued • Insulators and conductors can be charged by contact. • Conductors can be charged byinduction. • Induction is a process of charging a conductor by bringing it near another charged object and grounding the conductor.

8. Chapter 16 Visual Concepts Charging by Induction Click below to watch the Visual Concept. Visual Concept

9. Chapter 16 Section 1 Electric Charge Transfer of Electric Charge, continued • A surface charge can be induced on insulators bypolarization. • With polarization, the charges within individual molecules are realigned such that the molecule has a slight charge separation.

10. Chapter 16 Section 2 Electric Force Objectives • Calculateelectric force using Coulomb’s law. • Compareelectric force with gravitational force. • Applythe superposition principle to find the resultant force on a charge and to find the position at which the net force on a charge is zero.

11. Chapter 16 Section 2 Electric Force Coulomb’s Law • Two charges near one another exert a force on one another called theelectric force. • Coulomb’s law states that the electric force is propor-tional to the magnitude of each charge and inversely proportional to the square of the distance between them.

12. Chapter 16 Section 2 Electric Force Superposition Principle Click below to watch the Visual Concept. Visual Concept

13. Chapter 16 Section 2 Electric Force Coulomb’s Law, continued • The Coulomb force is a field force. • A field force is a force that is exerted by one object on another even though there is no physical contact between the two objects.

14. Chapter 16 Section 3 The Electric Field Electric Field Strength • Anelectric fieldis a region where an electric force on a test charge can be detected. • The SI units of the electric field, E, are newtons per coulomb (N/C). • The direction of the electric field vector, E,is in the direction of the electric force that would be exerted on a small positive test charge.

15. Chapter 16 Section 3 The Electric Field Electric Fields and Test Charges Click below to watch the Visual Concept. Visual Concept

16. Chapter 16 Section 3 The Electric Field Electric Field Strength, continued • Electric field strength depends on charge and distance. An electric field exists in the region around a charged object. • Electric Field Strength Due to a Point Charge

17. Chapter 16 Section 3 The Electric Field Calculating Net Electric Field Click below to watch the Visual Concept. Visual Concept

18. Chapter 16 Section 3 The Electric Field Electric Field Lines • The number of electric field lines is proportional to the electric field strength. • Electric field lines are tangent to the electric field vector at any point.

19. Chapter 16 Section 3 The Electric Field Rules for Drawing Electric Field Lines Click below to watch the Visual Concept. Visual Concept

20. Chapter 16 Section 3 The Electric Field Rules for Sketching Fields Created by Several Charges Click below to watch the Visual Concept. Visual Concept

21. Chapter 17 Section 1 Electric Potential Electrical Potential Energy • Electrical potential energy is potential energy associated with a charge due to its position in an electric field. • Electrical potential energy is a component of mechanical energy. ME = KE + PEgrav + PEelastic + PEelectric

22. Chapter 17 Section 1 Electric Potential Electrical Potential Energy Click below to watch the Visual Concept. Visual Concept

23. Chapter 17 Section 1 Electric Potential Potential Difference • Electric Potentialequals the work that must be performed against electric forces to move a charge from a reference point to the point in question, divided by the charge. • The electric potential associated with a charge is the electric energy divided by the charge:

24. Chapter 17 Section 1 Electric Potential Potential Difference, continued • Potential Difference equals the work that must be performed against electric forces to move a charge between the two points in question, divided by the charge. • Potential difference is a change in electric potential.

25. Chapter 17 Section 1 Electric Potential Potential Difference Click below to watch the Visual Concept. Visual Concept

26. Chapter 17 Section 1 Electric Potential Potential Difference, continued • The potential difference in a uniform field varies with the displacement from a reference point. • Potential Difference in a Uniform Electric Field ∆V = –Ed potential difference = –(magnitude of the electric field  displacement)

27. Chapter 17 Section 2 Capacitance Capacitors and Charge Storage • A capacitoris a device that is used to store electrical potential energy. • Capacitance is the ability of a conductor to store energy in the form of electrically separated charges. • The SI units for capacitance is thefarad,F, which equals a coulomb per volt (C/V)

28. Chapter 17 Section 2 Capacitance Capacitors and Charge Storage, continued • Capacitanceis the ratio of charge to potential difference.

29. Chapter 17 Section 2 Capacitance Capacitance Click below to watch the Visual Concept. Visual Concept

30. Chapter 17 Section 2 Capacitance Capacitors and Charge Storage, continued • Capacitancedepends on the size and shape of a capacitor. • Capacitance for a Parallel-Plate Capacitor in a Vacuum

31. Chapter 17 Section 2 Capacitance Capacitors in Keyboards

32. Chapter 17 Section 2 Capacitance Parallel-Plate Capacitor Click below to watch the Visual Concept. Visual Concept