physics ii: electricity & magnetism chapter 21 sections 21-1 to 21-4 chapter 21 sections 21-1 to...

Physics II:Electricity & Magnetism

Physics II:Electricity & Magnetism

Chapter 21Sections 21-1 to 21-4

Chapter 21Sections 21-1 to 21-4

Thursday (Day 2)

Thursday (Day 2)

Journal EntryJournal Entry

Thurs, Jan 22 What is the charge of a proton? What is the charge of an electron? What happens to a _______ charge when a _______ charge is

around it? positive; negative positive; positive negative; negative negative; positive

Place your homework on my desk: Student Information Sheet “What do you know?” Packet (Part I) & Scantron

Thurs, Jan 22 What is the charge of a proton? What is the charge of an electron? What happens to a _______ charge when a _______ charge is

around it? positive; negative positive; positive negative; negative negative; positive

Place your homework on my desk: Student Information Sheet “What do you know?” Packet (Part I) & Scantron

Warm-UpWarm-Up

Wed, Jan 21 Pick up the following handouts and find your seat:

“Foundational Mathematics’ Skills of Physics” Packet

Place your homework on my desk: Not Applicable

Wed, Jan 21 Pick up the following handouts and find your seat:

“Foundational Mathematics’ Skills of Physics” Packet

Place your homework on my desk: Not Applicable

Essential Question(s)Essential Question(s)

WHAT PRIOR FOUNDATIONAL MATHEMATICS’ SKILLS ARE NECESSARY IN PHYSICS II?

HOW DO WE DESCRIBE THE NATURE OF ELECTROSTATICS AND APPLY IT TO VARIOUS SITUATIONS?How do we describe and apply the concept of electric field?How do we compare and contrast the basic properties of an

insulator and a conductor?How do we describe and apply the concept of induced charge and

electrostatic shielding?How do we describe and apply Coulomb’s Law and the Principle

of Superposition?





of Superposition?

VocabularyVocabulary

Static ElectricityElectric ChargePositive / NegativeAttraction / RepulsionCharging / DischargingFriction InductionConductionLaw of Conservation of

Electric Charge


Electric Charge

Non-polar MoleculesPolar Molecules Ion Ionic CompoundsForceTest ChargeElectric FieldField LinesElectric DipoleDipole Moment


Foundational Mathematics Skills in Physics Timeline


Day Pg(s) Day Pg(s) Day Pg(s) Day Pg(s)

11

26 3 11 16 16 21

213

147 4 12 17 17 8

322

238 5 13 18 18 9

424†12

9 6 14 19 19 10

5 15 10 7 15 20 20 11


AgendaAgenda

Introduction to Electrostatics

Pick up the following handouts:“Foundational Mathematics’ Skills of Physics” Packet“What do you know?” Packet (Part II)

Introduction to Electrostatics

Pick up the following handouts:“Foundational Mathematics’ Skills of Physics” Packet“What do you know?” Packet (Part II)

Chapters 21 & 22

Electric Charge and Electric Field; Gauss’s Law

Units of Chapter 21

• Static Electricity; Electric Charge and Its Conservation

• Electric Charge in the Atom

• Insulators and Conductors

• Induced Charge; the Electroscope

• Coulomb’s Law

• Solving Problems Involving Coulomb’s Law and Vectors

• The Electric Field

Units of Chapter 21 & 22

• Field Lines

• Electric Fields and Conductors

Chaper 22

•Electric Flux

•Gauss’s Law

• Electric Forces in Molecular Biology: DNA Structure and Replication

Section 21.1Section 21.1

How do we describe and apply the concept of electric field?How do we describe the characteristics of a

positive electric charge?How do we describe the characteristics of a

negative electric charge? How do we describe the law of conservation of

electric charge?

How do we describe and apply the concept of electric field?How do we describe the characteristics of a

positive electric charge?How do we describe the characteristics of a

negative electric charge? How do we describe the law of conservation of

electric charge?

21.1 Static Electricity; Electric Charge and Its Conservation

Objects can be charged by rubbing

21.1 Static Electricity; Electric Charge and Its

Conservation

Charge comes in two types, positive and negative; like charges repel and opposite charges attract

†Electricity comes from the Greek word elektron, which means “amber”

21.1 Static Electricity; Electric Charge and Its Conservation

Electric charge is conserved – the arithmetic sum of the total charge cannot change in any interaction.


How do we describe and apply the concept of electric field?How do we describe electric charge in an

atom?How do we describe electric charge in a

molecule (or formula unit)?

How do we describe and apply the concept of electric field?How do we describe electric charge in an

atom?How do we describe electric charge in a

molecule (or formula unit)?

21.2 Electric Charge in the Atom

Atom:

Nucleus (small, massive, positive charge)

Electron cloud (large, very low density, negative charge)

Parts of the AtomParts of the Atom

Location: NucleusProton

Charge: 1.60 x 10-19 CoulombsMass: 1.6726 x 10-27 kgMade of 2 up quarks and 1 down quark

NeutronCharge: Neutral (0 Coulombs)Mass: 1.6749 x 10-27 kgMade of 2 down quarks and 1 up quark

Location: Energy Levels in the Electron CloudElectrons

Charge: -1.60 x 10-19 CoulombsMass: 9.11 x 10-31 kg

Location: NucleusProton

Charge: 1.60 x 10-19 CoulombsMass: 1.6726 x 10-27 kgMade of 2 up quarks and 1 down quark

NeutronCharge: Neutral (0 Coulombs)Mass: 1.6749 x 10-27 kgMade of 2 down quarks and 1 up quark

Location: Energy Levels in the Electron CloudElectrons

Charge: -1.60 x 10-19 CoulombsMass: 9.11 x 10-31 kg

The Size of the NucleusThe Size of the Nucleus

Almost all of the mass of the atom is concentrated in its tiny nucleus.

Next Slide: the football field illustration.

Almost all of the mass of the atom is concentrated in its tiny nucleus.

Next Slide: the football field illustration.

If the nucleus were the size of a pinhead . . .

If the nucleus were the size of a pinhead . . .

The Low Density of theElectron Cloud Model

The Low Density of theElectron Cloud Model

The low density of the electron cloud is due to the fact that (1) the mass of one proton is equal to the mass of 1,836 electrons and (2) the electrons are arranged in the energy levels that are far from the nucleus.

The proton has 1,836 times more inertia than an electron and is therefore 1,836 times harder to move than an electron.

The low density of the electron cloud is due to the fact that (1) the mass of one proton is equal to the mass of 1,836 electrons and (2) the electrons are arranged in the energy levels that are far from the nucleus.

The proton has 1,836 times more inertia than an electron and is therefore 1,836 times harder to move than an electron.

INERTIAA Proton vs. an Electron

INERTIAA Proton vs. an Electron

Recall Newton’s Second Law of Motion

Force = mass x acceleration

The proton has 1,836 times more mass (aka. Inertia) than an electron and is therefore 1,836 times harder to move than an electron.

Recall Newton’s Second Law of Motion

Force = mass x acceleration

The proton has 1,836 times more mass (aka. Inertia) than an electron and is therefore 1,836 times harder to move than an electron.

Electron Cloud ModelElectron Cloud Model

The probability of locating an electron 90% of the time is determined by utilizing the Schrödinger equation and statistics.

The probability of locating an electron 90% of the time is determined by utilizing the Schrödinger equation and statistics.


Atom is electrically neutral.

Rubbing charges objects by moving electrons from one to the other.

Chemical Bonding

Atoms bond together to form electrically neutral substances.

The type of chemical bond is determined by the electronegativity difference between the atoms involved.

Electronegativity Values:The Affinity for ElectronsElectronegativity Values:The Affinity for Electrons

Electronegativity Difference and Bond Type

Electronegativity Difference and Bond Type

Electronegativity Difference

Bond Type

EN: 0.0 - 0.4 Nonpolar Covalent Bond

EN: 0.41 - 1.65 Polar Covalent Bond

EN: 1.66 and greater

Ionic Bond

Nonpolar Covalent Molecules

Nonpolar Covalent Molecules

Electronegativity Difference: 0.0 - 0.4 Description: Shares electrons evenly Examples: H2, CH4, Cl2, O2, Br2, I2, etc.

They are generally gases at room temperature because they have little or †no attraction to other nonpolar molecules Exceptions:

Bromine (Br2) is a liquid (70 total electrons/molecule)

Iodine (I2) is a solid (106 total electrons/molecule)

†A Temporary Dipoles can establish an attractive force if the molecules (1) get close enough and (2) are not moving fast.

Electronegativity Difference: 0.0 - 0.4 Description: Shares electrons evenly Examples: H2, CH4, Cl2, O2, Br2, I2, etc.

They are generally gases at room temperature because they have little or †no attraction to other nonpolar molecules Exceptions:

Bromine (Br2) is a liquid (70 total electrons/molecule)

Iodine (I2) is a solid (106 total electrons/molecule)

†A Temporary Dipoles can establish an attractive force if the molecules (1) get close enough and (2) are not moving fast.

Temporary DipoleTemporary Dipole

Polar Covalent MoleculesPolar Covalent Molecules Electronegativity Difference: 0.41 - 1.65 Description: Shares electrons unevenly Examples: H2O, NH3

They are generally liquids or solids at room temperature because their permanent dipoles (slightly positive and slightly negative parts) attract their counterparts of other polar molecules and †many polar molecules are able to group together. Example: Water Droplets

†

Electronegativity Difference: 0.41 - 1.65 Description: Shares electrons unevenly Examples: H2O, NH3

They are generally liquids or solids at room temperature because their permanent dipoles (slightly positive and slightly negative parts) attract their counterparts of other polar molecules and †many polar molecules are able to group together. Example: Water Droplets

†1 drop x

1 mL

20 dropsx

1 g

1 mLx

1 mole

18.02 gx

6.022x1023 molecules

1 mole=


Polar molecule: neutral overall, but charge not evenly distributed

Dipole-Dipole BondingDipole-Dipole Bonding

Dipole-Dipole BondsDipole-Dipole Bonds

Ionic Compounds(aka. Formula Units)

Ionic Compounds(aka. Formula Units)

Electronegativity Difference: 1.66 and above Description: “†Transfers” electrons from one atom to another

creating an attraction due to the charge of each atom. Examples: NaCl, CaCl2, MgO, KI, CuCl2 They are solids at room temperature because their

†permanent positive charges attract all other negative charges and a negative charge is attracted to all of the positive charges. This creates a large repeating structure known as a crystal lattice.

†In reality, the electron that has been transferred is still being attracted by the nucleus of the atom that has “lost” the electron, but the ratio of this attraction to the atom that has gained it is relatively small. i.e. Cl-/Na+: 3.16/0.93 ≈ 3; The transferred electron is attracted 3 times

more to the Cl ion than the Na ion.

Electronegativity Difference: 1.66 and above Description: “†Transfers” electrons from one atom to another

creating an attraction due to the charge of each atom. Examples: NaCl, CaCl2, MgO, KI, CuCl2 They are solids at room temperature because their

†permanent positive charges attract all other negative charges and a negative charge is attracted to all of the positive charges. This creates a large repeating structure known as a crystal lattice.

†In reality, the electron that has been transferred is still being attracted by the nucleus of the atom that has “lost” the electron, but the ratio of this attraction to the atom that has gained it is relatively small. i.e. Cl-/Na+: 3.16/0.93 ≈ 3; The transferred electron is attracted 3 times

more to the Cl ion than the Na ion.

Crystal Lattice: NaClCrystal Lattice: NaCl

SummarySummary

In regards to Electricity & Magnetism, write down: 3 things you already knew from today2 things that you learned today1 thing you would like to know

HW (Place in your agenda): “Foundational Mathematics’ Skills of Physics” Packet

(Page 1 & 2)

TEACHER HOMEWORK: BUY MYLAR BALLOONS AND SCOTCH TAPE

In regards to Electricity & Magnetism, write down: 3 things you already knew from today2 things that you learned today1 thing you would like to know


(Page 1 & 2)

TEACHER HOMEWORK: BUY MYLAR BALLOONS AND SCOTCH TAPE

Friday (Day 3)Friday (Day 3)

Warm-UpWarm-Up

Fri, Jan 23 Identify the three bond types and their characteristics

Pickup a LAB JOURNAL from my desk.

Place your homework on my desk:“Foundational Mathematics’ Skills of Physics” Packet

(Page 1 & 2)

Fri, Jan 23 Identify the three bond types and their characteristics

Pickup a LAB JOURNAL from my desk.

Place your homework on my desk:“Foundational Mathematics’ Skills of Physics” Packet

(Page 1 & 2)






of Superposition?





of Superposition?



Electric Charge


Electric Charge






11

26 3 11 16 16 21

213

147 4 12 17 17 8

322

238 5 13 18 18 9

424†12

9 6 14 19 19 10

5 15 10 7 15 20 20 11


AgendaAgenda

Review “Foundational Mathematics’ Skills of Physics” Packet (Page 1 & 2) with answer guide in the back of the class

Introduction to Insulators and conductors

Begin Electrostatics Lab

Review “Foundational Mathematics’ Skills of Physics” Packet (Page 1 & 2) with answer guide in the back of the class

Introduction to Insulators and conductors

Begin Electrostatics Lab


How do we compare and contrast the basic properties of an insulator and a conductor?What are characteristics and classification(s) of

electrically . . .conductive atoms?insulative atoms?semi-conductive atoms?conductive compounds?insulative compounds?semi-conductive compounds?

How do we compare and contrast the basic properties of an insulator and a conductor?What are characteristics and classification(s) of

electrically . . .conductive atoms?insulative atoms?semi-conductive atoms?conductive compounds?insulative compounds?semi-conductive compounds?

21.3 Insulators and Conductors

Conductor:

Charge flows freely

Metals

Insulator:

Almost no charge flows

Most other materials

Some materials are semiconductors.

Why are certain atoms conductors and other insulators?

Why are certain atoms conductors and other insulators?

Recall on the periodic table that there are elements that do not react known as the Noble Gases. This is because their valence or outer energy levels contain 8 electrons (†Helium only has 2 because it has only 1 energy level)

If possible other atoms on the periodic table will try to gain or lose electrons to acquire the same electron configurations as the Noble Gases.

Recall on the periodic table that there are elements that do not react known as the Noble Gases. This is because their valence or outer energy levels contain 8 electrons (†Helium only has 2 because it has only 1 energy level)

If possible other atoms on the periodic table will try to gain or lose electrons to acquire the same electron configurations as the Noble Gases.

A Conductor or an Insulator?A Conductor or an Insulator?

Are the following elements conductors or insulators? Justify your answer.SodiumChlorineOxygenPotassiumMagnesiumAluminumSilicon

Are the following elements conductors or insulators? Justify your answer.SodiumChlorineOxygenPotassiumMagnesiumAluminumSilicon

Sodium is a conductor because it loses electrons easily.

Sodium is a conductor because it loses electrons easily.

- 1 e-NaNa+Neon’s Electron

Configuration


How do we describe and apply the concept of induced charge and electrostatic shielding?How do we qualitatively explain the process of

charging by induction?How does an electroscope detect charge?

How do we describe and apply the concept of induced charge and electrostatic shielding?How do we qualitatively explain the process of

charging by induction?How does an electroscope detect charge?

21.4 Induced Charge; the Electroscope

Metal objects can be charged by conduction:


They can also be charged by induction:

What does it mean to be “grounded“?


You must stay in the house for a week.You have lost your privilegesYou are in real trouble young man

Or

You are firm in your belief of high morality.

You must stay in the house for a week.You have lost your privilegesYou are in real trouble young man

Or

You are firm in your belief of high morality.



An object is said to be “grounded” or “earthed” when it is connected to a conducting wire or pipe leading into the ground.

Because the Earth is so large and can conduct electricity, it can easily accept or give up electrons. It is essentially a large reservoir or sink hole for (negative) electric charge (aka. electrons).

An object is said to be “grounded” or “earthed” when it is connected to a conducting wire or pipe leading into the ground.

Because the Earth is so large and can conduct electricity, it can easily accept or give up electrons. It is essentially a large reservoir or sink hole for (negative) electric charge (aka. electrons).

What would happen if . . .What would happen if . . .

a negatively-charged object were allowed to touch a ...metal faucet that was connected to ground

and the pipe were chopped off with a super axe hacker . . .before the negatively-charged object was

removedafter the negatively-charged object was removed

a negatively-charged object were allowed to touch a ...metal faucet that was connected to ground




a metal faucet that was connected to ground and the pipe were chopped off with a super axe hacker and a negatively-charged object were allowed to touch it . . .and the negatively-charged object were

then removed.

a metal faucet that was connected to ground and the pipe were chopped off with a super axe hacker and a negatively-charged object were allowed to touch it . . .and the negatively-charged object were

then removed.


a negatively-charged object were brought near a ...metal faucet that was connected to ground



a negatively-charged object were brought near a ...metal faucet that was connected to ground




a metal faucet that was connected to ground and the pipe were chopped off with a super axe hacker and a negatively-charged object were brought near it. . .and the negatively-charged object were

then removed.

a metal faucet that was connected to ground and the pipe were chopped off with a super axe hacker and a negatively-charged object were brought near it. . .and the negatively-charged object were

then removed.


a positively-charged object were allowed to touch a ...metal faucet that was connected to ground

and the pipe were chopped off with a super axe hacker . . .before the positively-charged object was removedafter the positively-charged object was removed

a positively-charged object were allowed to touch a ...metal faucet that was connected to ground



a metal faucet that was connected to ground and the pipe were chopped off with a super axe hacker and a positively-charged object were allowed to touch it . . .and the positively-charged object were then

removed.

a metal faucet that was connected to ground and the pipe were chopped off with a super axe hacker and a positively-charged object were allowed to touch it . . .and the positively-charged object were then

removed.


a positively-charged object were brought near a ...metal faucet that was connected to ground


a positively-charged object were brought near a ...metal faucet that was connected to ground



a metal faucet that was connected to ground and the pipe were chopped off with a super axe hacker and a positively-charged object were brought near it. . .and the positively-charged object were then

removed.

a metal faucet that was connected to ground and the pipe were chopped off with a super axe hacker and a positively-charged object were brought near it. . .and the positively-charged object were then

removed.


a negatively-charged piece of plastic were allowed to touch a ...metal faucet that was connected to ground

and the pipe were chopped off with a super axe hacker . . .before the negatively-charged piece of plastic

was removedafter the negatively-charged piece of plastic was

removed

a negatively-charged piece of plastic were allowed to touch a ...metal faucet that was connected to ground

and the pipe were chopped off with a super axe hacker . . .before the negatively-charged piece of plastic

was removedafter the negatively-charged piece of plastic was

removed


a positively-charged glass rod were allowed to touch a ...metal faucet that was connected to ground

and the pipe were chopped off with a super axe hacker . . .before the positively-charged glass rod was

removedafter the positively-charged glass rod was

removed

a positively-charged glass rod were allowed to touch a ...metal faucet that was connected to ground

and the pipe were chopped off with a super axe hacker . . .before the positively-charged glass rod was

removedafter the positively-charged glass rod was

removed

Electrostatics Lab #1Electrostatics Lab #1

5 Charge StationsDensity of Water

Graph: mass vs. volumeCalculate the slope

Water droplet/ml#of water droplets on pennyAvogadro’s number

5 Charge StationsDensity of Water

Graph: mass vs. volumeCalculate the slope

Water droplet/ml#of water droplets on pennyAvogadro’s number

SummarySummary

Identify two differences between insulators and conductors


(Page 13 & 14)

Identify two differences between insulators and conductors


(Page 13 & 14)

Monday (Day 4)Monday (Day 4)

Warm-UpWarm-Up

Mon, Jan 26 Identify the charges on the

Amber rodFurGlass RodSilk

Have you logged onto webassign.net? Place your homework on my desk:

“Foundational Mathematics’ Skills of Physics” Packet (Page 13 & 14)

Mon, Jan 26 Identify the charges on the

Amber rodFurGlass RodSilk

Have you logged onto webassign.net? Place your homework on my desk:

“Foundational Mathematics’ Skills of Physics” Packet (Page 13 & 14)






of Superposition?





of Superposition?



Electric Charge


Electric Charge






11

26 3 11 16 16 21

213

147 4 12 17 17 8

322

238 5 13 18 18 9

424†12

9 6 14 19 19 10

5 15 10 7 15 20 20 11


AgendaAgenda

Review “Foundational Mathematics’ Skills of Physics” Packet (Page 13 & 14) with answer guide in the back of the class.

Discuss induction in insulators and electroscopes Complete Electrostatics Lab #1 & 2

Review “Foundational Mathematics’ Skills of Physics” Packet (Page 13 & 14) with answer guide in the back of the class.

Discuss induction in insulators and electroscopes Complete Electrostatics Lab #1 & 2


Nonconductors won’t become charged by conduction or induction, but will experience charge separation:

Electron Cloud PolarizationElectron Cloud Polarization

Similar to the Temporary Dipole in I2

Similar to the Temporary Dipole in I2


The electroscope can be used for detecting charge:

21.4 Induced Charge; the ElectroscopeThe electroscope can be charged either by conduction or by induction.


The charged electroscope can then be used to determine the sign of an unknown charge.

SummarySummary

What happens to the electrons in an insulator during the process of “charging by” induction?


(Page 22 - 23)Electrostatics Lab #1: Lab Report (Due in 6 classes)

What happens to the electrons in an insulator during the process of “charging by” induction?


(Page 22 - 23)Electrostatics Lab #1: Lab Report (Due in 6 classes)

physics ii: electricity & magnetism chapter 21 sections 21-1 to 21-4 chapter 21 sections 21-1 to...

Documents

concept of induced charge

concept of electric

applicable slide

scantron slide

following handouts

nature of electrostatics

coulomb s law

electricity magnetism