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

Chapter 16 Objectives Understand the basic properties of electric charge. Differentiate between conductors and insulators. Distinguish between charging by contact, charging by induction, and charging by polarization.

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 called protons. –Uncharged particles are called neutrons. –Negatively charged particles are called electrons.

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

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 a fundamental 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 = x 10 –19 C

Chapter 16 The Milikan Experiment Section 1 Electric Charge

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

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

Section 2 Electric Force Chapter 16 Objectives Calculate electric force using Coulomb’s law. Compare electric force with gravitational force. Apply the 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.

Chapter 16 Coulomb’s Law Two charges near one another exert a force on one another called the electric 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. Section 2 Electric Force

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

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. Chapter 16 Section 2 Electric Force

Chapter 16 Section 3 The Electric Field Electric Field Strength An electric field is 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.

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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

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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.

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

Section 1 Electric Potential Chapter 17 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 + PE grav + PE elastic + PE electric

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Section 1 Electric Potential Chapter 17 Potential Difference Electric Potential equals 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:

Section 1 Electric Potential Chapter 17 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.

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Section 1 Electric Potential Chapter 17 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)

Section 2 Capacitance Chapter 17 Capacitors and Charge Storage A capacitor is 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 the farad, F, which equals a coulomb per volt (C/V)

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

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

Chapter 17 Capacitors in Keyboards Section 2 Capacitance

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