Physics II: Electricity & Magnetism Sections 23.1 to 23.9

Friday (Day 1)

Warm-Up Fri, Feb 27 Our scenario: A ball is being dropped from a height, a, and will hit the ground, b. Using your knowledge and the law of conservation of energy, make a chart to generally Our scenario: A ball is being dropped from a height, a, and will hit the ground, b. Using your knowledge and the law of conservation of energy, make a chart to generally Identify the direction of the gravitational field. (I.e. up, down, left,right, etc) Identify the direction of the gravitational field. (I.e. up, down, left,right, etc) The potential energy at (a) point a and (b) point b. (I.e. high, low, same) The potential energy at (a) point a and (b) point b. (I.e. high, low, same) The potential to do work at (a) point a and (b) point b. (I.e. high, low, same) The potential to do work at (a) point a and (b) point b. (I.e. high, low, same) The kinetic energy at (a) point a and (b) point b. (I.e. high, low, same) The kinetic energy at (a) point a and (b) point b. (I.e. high, low, same) The change in potential energy, potential to do work, and kinetic energy as it moves from a to b. (I.e. increase, decrease, constant) The change in potential energy, potential to do work, and kinetic energy as it moves from a to b. (I.e. increase, decrease, constant) The work done by gravity (I.e. positive, negative, none) The work done by gravity (I.e. positive, negative, none) Place your homework on my desk: Place your homework on my desk: No homework No homework For future assignments - check online at For future assignments - check online at Fri, Feb 27 Our scenario: A ball is being dropped from a height, a, and will hit the ground, b. Using your knowledge and the law of conservation of energy, make a chart to generally Our scenario: A ball is being dropped from a height, a, and will hit the ground, b. Using your knowledge and the law of conservation of energy, make a chart to generally Identify the direction of the gravitational field. (I.e. up, down, left,right, etc) Identify the direction of the gravitational field. (I.e. up, down, left,right, etc) The potential energy at (a) point a and (b) point b. (I.e. high, low, same) The potential energy at (a) point a and (b) point b. (I.e. high, low, same) The potential to do work at (a) point a and (b) point b. (I.e. high, low, same) The potential to do work at (a) point a and (b) point b. (I.e. high, low, same) The kinetic energy at (a) point a and (b) point b. (I.e. high, low, same) The kinetic energy at (a) point a and (b) point b. (I.e. high, low, same) The change in potential energy, potential to do work, and kinetic energy as it moves from a to b. (I.e. increase, decrease, constant) The change in potential energy, potential to do work, and kinetic energy as it moves from a to b. (I.e. increase, decrease, constant) The work done by gravity (I.e. positive, negative, none) The work done by gravity (I.e. positive, negative, none) Place your homework on my desk: Place your homework on my desk: No homework No homework For future assignments - check online at For future assignments - check online at

Scenario #1: A ball is being dropped from a height, a, and will hit the ground, b. a b Direction Of Gravity Direction Of Motion

Gravitational Field and Energy Using your knowledge and the law of conservation of energy, make a chart to generally Using your knowledge and the law of conservation of energy, make a chart to generally Identify the direction of the gravitational field. (I.e. up, down, left,right, etc) Identify the direction of the gravitational field. (I.e. up, down, left,right, etc) The potential energy at (a) point a and (b) point b. (I.e. high, low, same) The potential energy at (a) point a and (b) point b. (I.e. high, low, same) The potential to do work at (a) point a and (b) point b. (I.e. high, low, same) The potential to do work at (a) point a and (b) point b. (I.e. high, low, same) The kinetic energy at (a) point a and (b) point b. (I.e. high, low, same) The kinetic energy at (a) point a and (b) point b. (I.e. high, low, same) The change in potential energy, potential to do work, and kinetic energy as it moves from a to b. (I.e. increase, decrease, constant) The change in potential energy, potential to do work, and kinetic energy as it moves from a to b. (I.e. increase, decrease, constant) The work done by gravity (I.e. positive, negative, none) The work done by gravity (I.e. positive, negative, none) ADDITION: Write the formula’s for work, potential energy, and kinetic energy. ADDITION: Write the formula’s for work, potential energy, and kinetic energy. Using your knowledge and the law of conservation of energy, make a chart to generally Using your knowledge and the law of conservation of energy, make a chart to generally Identify the direction of the gravitational field. (I.e. up, down, left,right, etc) Identify the direction of the gravitational field. (I.e. up, down, left,right, etc) The potential energy at (a) point a and (b) point b. (I.e. high, low, same) The potential energy at (a) point a and (b) point b. (I.e. high, low, same) The potential to do work at (a) point a and (b) point b. (I.e. high, low, same) The potential to do work at (a) point a and (b) point b. (I.e. high, low, same) The kinetic energy at (a) point a and (b) point b. (I.e. high, low, same) The kinetic energy at (a) point a and (b) point b. (I.e. high, low, same) The change in potential energy, potential to do work, and kinetic energy as it moves from a to b. (I.e. increase, decrease, constant) The change in potential energy, potential to do work, and kinetic energy as it moves from a to b. (I.e. increase, decrease, constant) The work done by gravity (I.e. positive, negative, none) The work done by gravity (I.e. positive, negative, none) ADDITION: Write the formula’s for work, potential energy, and kinetic energy. ADDITION: Write the formula’s for work, potential energy, and kinetic energy.

Gravitational Field and Energy Field:   y :  cos  = cos(0) =1 Potential Energy Potential to do Work Kinetic Energy Initial Location (a)  y 0 = 0 High Low Final Location (b) Low High Change  PE = PE b - PE a  – Decreases,   Potential = Pot b - Pot a  – Decreases,   KE = KE b - KE a  + Increases 

Electric Field and Energy Using your knowledge and the law of conservation of energy, make a chart to generally Using your knowledge and the law of conservation of energy, make a chart to generally Identify the direction of the electric field. (I.e. up, down, left,right, etc) Identify the direction of the electric field. (I.e. up, down, left,right, etc) The potential energy at (a) point a and (b) point b. (I.e. high, low, same) The potential energy at (a) point a and (b) point b. (I.e. high, low, same) The potential to do work at (a) point a and (b) point b. (I.e. high, low, same) The potential to do work at (a) point a and (b) point b. (I.e. high, low, same) The kinetic energy at (a) point a and (b) point b. (I.e. high, low, same) The kinetic energy at (a) point a and (b) point b. (I.e. high, low, same) The change in potential energy, potential to do work, and kinetic energy as it moves from a to b. (I.e. increase, decrease, constant) The change in potential energy, potential to do work, and kinetic energy as it moves from a to b. (I.e. increase, decrease, constant) The work done by the electric field (I.e. positive, negative, none) The work done by the electric field (I.e. positive, negative, none) Using your knowledge and the law of conservation of energy, make a chart to generally Using your knowledge and the law of conservation of energy, make a chart to generally Identify the direction of the electric field. (I.e. up, down, left,right, etc) Identify the direction of the electric field. (I.e. up, down, left,right, etc) The potential energy at (a) point a and (b) point b. (I.e. high, low, same) The potential energy at (a) point a and (b) point b. (I.e. high, low, same) The potential to do work at (a) point a and (b) point b. (I.e. high, low, same) The potential to do work at (a) point a and (b) point b. (I.e. high, low, same) The kinetic energy at (a) point a and (b) point b. (I.e. high, low, same) The kinetic energy at (a) point a and (b) point b. (I.e. high, low, same) The change in potential energy, potential to do work, and kinetic energy as it moves from a to b. (I.e. increase, decrease, constant) The change in potential energy, potential to do work, and kinetic energy as it moves from a to b. (I.e. increase, decrease, constant) The work done by the electric field (I.e. positive, negative, none) The work done by the electric field (I.e. positive, negative, none)

Scenario #2: A charge in an electric field is being “dropped” from a point a, and will hit the plate at point b. b Direction of E Direction of Motion a +-- b a

Electric Field and Energy (Positive Charge) Field:   x:  cos  = cos(0) =1 Initial Location (a)  x 0 = 0 Final Location (b) Change Potential Energy HighLow  PE =  U = U b - U a  – Decreases,  Potential to do Work HighLow  Potential =  V = V b - V a  – Decreases,  Kinetic EnergyLowHigh  KE =  K = K b - K a  + Increases 

Electric Field and Energy (Negative Charge) Field:   x:  cos(180) = –1 Initial Location (a)  x 0 = 0 Final Location (b) Change Potential Energy HighLow  PE =  U = U b - U a  – Decreases,  Potential to do Work HighLow  Potential =  V = V b - V a  – Decreases,  Kinetic EnergyLowHigh  KE =  K = K b - K a  + Increases 

6-1 Work Done by a Constant Force The work done by a constant force is defined as the distance moved multiplied by the component of the force in the direction of displacement: (6-1)

6-3 Kinetic Energy, and the Work-Energy Principle This means that the work done is equal to the change in the kinetic energy: If the net work is positive, the kinetic energy increases. If the net work is negative, the kinetic energy decreases. (6-4)

6-5 Conservative and Nonconservative Forces Potential energy can only be defined for conservative forces.

6-6 Mechanical Energy and Its Conservation If there are no nonconservative forces, the sum of the changes in the kinetic energy and in the potential energy is zero – the kinetic and potential energy changes are equal but opposite in sign. This allows us to define the total mechanical energy: And its conservation:

Essential Question(s) HOW DO WE DESCRIBE AND APPLY THE CONCEPT OF ELECTRIC POTENTIAL? HOW DO WE DESCRIBE AND APPLY THE CONCEPT OF ELECTRIC POTENTIAL? How do we calculate the electrical work done on a positive and negative charge that moves through a potential difference? How do we calculate the electrical work done on a positive and negative charge that moves through a potential difference? How do we apply the Law of Conservation of Energy to determine the speed of a charged particle that has been accelerated through a potential difference? How do we apply the Law of Conservation of Energy to determine the speed of a charged particle that has been accelerated through a potential difference? How do we describe and apply the concept of electric fields? How do we describe and apply the concept of electric fields? HOW DO WE DESCRIBE AND APPLY THE CONCEPT OF ELECTRIC POTENTIAL? HOW DO WE DESCRIBE AND APPLY THE CONCEPT OF ELECTRIC POTENTIAL? How do we calculate the electrical work done on a positive and negative charge that moves through a potential difference? How do we calculate the electrical work done on a positive and negative charge that moves through a potential difference? How do we apply the Law of Conservation of Energy to determine the speed of a charged particle that has been accelerated through a potential difference? How do we apply the Law of Conservation of Energy to determine the speed of a charged particle that has been accelerated through a potential difference? How do we describe and apply the concept of electric fields? How do we describe and apply the concept of electric fields?

Vocabulary Electric Potential Electric Potential Potential Potential Difference in Potential Difference in Potential Potential Difference Potential Difference Volt Volt Voltage Voltage Equipotential Lines Equipotential Lines Equipotential Surfaces Equipotential Surfaces Electric Dipole Electric Dipole Electric Potential Electric Potential Potential Potential Difference in Potential Difference in Potential Potential Difference Potential Difference Volt Volt Voltage Voltage Equipotential Lines Equipotential Lines Equipotential Surfaces Equipotential Surfaces Electric Dipole Electric Dipole Dipole Moment Electron Volt Cathode Ray Tube Thermionic Emission Cathode Anode Cathode Rays Oscilloscope

Foundational Mathematics Skills in Physics Timeline DayPg(s)DayPg(s)DayPg(s)DayPg(s) †

Agenda Review “Foundational Mathematics’ Skills of Physics” Packet (Page 16) with answer guide. Review “Foundational Mathematics’ Skills of Physics” Packet (Page 16) with answer guide. Discuss Discuss Electric Fields and Conductors Electric Fields and Conductors Motion of a Charged Particle in an Electric Field Motion of a Charged Particle in an Electric Field Work on Web Assign Work on Web Assign Review “Foundational Mathematics’ Skills of Physics” Packet (Page 16) with answer guide. Review “Foundational Mathematics’ Skills of Physics” Packet (Page 16) with answer guide. Discuss Discuss Electric Fields and Conductors Electric Fields and Conductors Motion of a Charged Particle in an Electric Field Motion of a Charged Particle in an Electric Field Work on Web Assign Work on Web Assign

Chapter 23 Electric Potential

Units of Chapter 23 Electric Potential and Potential Difference Relation between Electric Potential and Electric Field Electric Potential Due to Point Charges Electric Potential Due to Any Charge Distribution HOW DO WE DESCRIBE AND APPLY THE CONCEPT OF ELECTRIC POTENTIAL?

Units of Chapter 23 Equipotential Surfaces Electric Dipoles E Determined from V Electrostatic Potential Energy; The Electron Volt Cathode Ray Tube: TV and Computer Monitors, Oscilloscope HOW DO WE DESCRIBE AND APPLY THE CONCEPT OF ELECTRIC POTENTIAL?

21.6 The Electric Field Recall: The electric field is the force on a small charge, divided by the charge: Force on a point charge in an electric field: HOW DO WE DESCRIBE AND APPLY THE CONCEPT OF ELECTRIC POTENTIAL?

Electrostatic Potential Energy and Potential Difference Analogy between gravitational and electrical potential energy: HOW DO WE DESCRIBE AND APPLY THE CONCEPT OF ELECTRIC POTENTIAL?

Electrostatic Potential Energy and Potential Difference Because the electrostatic force is conservative, the potential energy can be defined. Change in electric potential energy is negative of work done by electric force: HOW DO WE DESCRIBE AND APPLY THE CONCEPT OF ELECTRIC POTENTIAL?

Electrostatic Potential Energy and Potential Difference Electric potential is defined as potential energy per unit charge: Unit of electric potential: the volt ( V ). 1 V = 1 J / C. Therefore by simple rearrangement, the potential energy can be related to the electric potential: HOW DO WE DESCRIBE AND APPLY THE CONCEPT OF ELECTRIC POTENTIAL?

Electrostatic Potential Energy and Potential Difference Work, Kinetic Energy, Potential Energy, Potential, and Potential Difference are all scalar quantities, therefore, they only have magnitude and not direction. Work, Kinetic Energy, Potential Energy, Potential, and Potential Difference are all scalar quantities, therefore, they only have magnitude and not direction. A positive W ba,  K,  U, or  V implies it increases, and a negative W ba,  K,  U, or  V implies it decreases. A positive W ba,  K,  U, or  V implies it increases, and a negative W ba,  K,  U, or  V implies it decreases. Work, Kinetic Energy, Potential Energy, Potential, and Potential Difference are all scalar quantities, therefore, they only have magnitude and not direction. Work, Kinetic Energy, Potential Energy, Potential, and Potential Difference are all scalar quantities, therefore, they only have magnitude and not direction. A positive W ba,  K,  U, or  V implies it increases, and a negative W ba,  K,  U, or  V implies it decreases. A positive W ba,  K,  U, or  V implies it increases, and a negative W ba,  K,  U, or  V implies it decreases. HOW DO WE DESCRIBE AND APPLY THE CONCEPT OF ELECTRIC POTENTIAL?

Electrostatic Potential Energy and Potential Difference Because only changes in potential and potential energy can be measured, Conveniently, this also allows for the free assignment of V = 0 and U = 0. HOW DO WE DESCRIBE AND APPLY THE CONCEPT OF ELECTRIC POTENTIAL?

Electrostatic Potential Energy and Potential Difference By reversing the previous derivation Work can then be related to the potential by: HOW DO WE DESCRIBE AND APPLY THE CONCEPT OF ELECTRIC POTENTIAL?

Summary Using the following electrostatic equations, develop their gravitational counterparts for force, gravitational field, potential energy and gravitational potential. Using the following electrostatic equations, develop their gravitational counterparts for force, gravitational field, potential energy and gravitational potential. HW (Place in your agenda): HW (Place in your agenda): Chapter 22 Web Assign Final Copy Chapter 22 Web Assign Final Copy Web Assign Web Assign Future assignments: Future assignments: Electrostatics Lab #4 Report (Due in 3 Classes) Electrostatics Lab #4 Report (Due in 3 Classes) Using the following electrostatic equations, develop their gravitational counterparts for force, gravitational field, potential energy and gravitational potential. Using the following electrostatic equations, develop their gravitational counterparts for force, gravitational field, potential energy and gravitational potential. HW (Place in your agenda): HW (Place in your agenda): Chapter 22 Web Assign Final Copy Chapter 22 Web Assign Final Copy Web Assign Web Assign Future assignments: Future assignments: Electrostatics Lab #4 Report (Due in 3 Classes) Electrostatics Lab #4 Report (Due in 3 Classes) HOW DO WE DESCRIBE AND APPLY THE CONCEPT OF ELECTRIC POTENTIAL?