Physics 114 – General Physics II Everyone Pick Up: Syllabus Student Info sheet – fill it out Materials Physics for Scientists and Engineers, 9th ed., Serway and Jewett, through chap. 40 Scientific Calculator* Tophat Laptop/Mobile Device* 30 cm metric ruler * - bring these to class Ryan Godwin “Professor (Dr.) Godwin” Olin 311 Office Hours always (520)-465-7476 (c) godwrc12@wfu.edu Topics Covered: 30% Electricity 30% Magnetism 30% Optics 10% Modern Physics http://users.wfu.edu/~godwrc12 https://app.tophat.com/e/214952

Dr. Godwin’s Schedule Monday Tuesday Wednesday Thursday Friday PHY 114 Office Hours 9:00 9:30 10:00 10:30 11:00 11:30 12:00

Preparing for Lecture Reading Assignment Website Overview Reading Assignment Sections 23.1 – 23.5 by Thursday Sections 23.6-7, 24.1-3 by Tuesday Quizzes: Reading quiz 23a by Thursday Reading quiz 23b by Tuesday Read the material assigned on the Web, or in class each day, before class starts Take a Tophat-based reading quiz online by 9:30 AM Tophat Introduction

Class attendance & Participation I grade a very small portion based on attendance It is basically necessary for class participation I will be taking attendance, at the very beginning of class via Tophat. Be on time! Do you understand how concept questions work? Yes, I’ve done it before Yes, it’s just like iClickers B) Yes, though it’s new to me C) Sort of, I’ll figure it out D) Huh? Class Participation Grade and in class questions I present a multiple choice question Round 1 – You must figure out or guess the answer, then vote with your mobile device or laptop You discuss the questions with your classmates Round 2 – You get a second chance to get the answer right Right answers: 4/4, wrong answers: 3/4 If you get 80% or more, you get full credit on class participation Participating in class discussion gains bonus points that can push up your participation grade, even past full credit

https://app.tophat.com/e/214952 Homework, Serway + Tophat https://app.tophat.com/e/214952 All homework will be based on questions in Serway. They will either be posted in the lecture notes (turn in on paper) or in Tophat Bookstore can sell you a license, or you can get it online Partial credit awarded – attempt each problem and work to completion Link to tophat is on the class web page Due weekly – every Tuesday at 9:30 AM You can work together, but everyone must turn in their own work Make sure you understand every problem – tests will make it clear if you don’t Getting help is encouraged Ask a friend, ask me, come to office hours First assignment is due on Tuesday of next week Groups will be provided to help you work on homework (or study, or whatever)

Exams Exam Dates: September 19 October 10 November 14 Dec 13, 2 PM 3 tests and a final Honors code violations will be turned in to the honor council Normally, penalty is 1-term suspension and an irreplaceable F in the course Multiple choice, short essay and computational problems If ill, call me/email me immediately or bring a Doctor’s note Exam Dates: September 19 October 10 November 14 Dec 13, 2 PM Red dashed line means you should be able to use this on a test, but you needn’t memorize it Red boxes mean memorize this for the test Other colors mean not on the test Dotted red means easily derived from other formulas

Miscellaneous The Web Pandemic Plans Labs Tutorials Numerous materials can be found on the web for this course Lectures Syllabus and other handouts Reading assignments and quizzes Test information Additional Resources If there is a catastrophic closing of the university, we will attempt to continue the class: Emergency contacts: Web page Email: godwrc12@wfu.edu Cell: 520-465-7476 http://users.wfu.edu/godwrc12/ Labs Tutorials You are required to sign up for PHY 114L You must pass the lab to pass the class Labs begin week of September 4th Days to be Determined Olin 101 Start next week?

Percentage Breakdown: Grades Percentage Breakdown: Test 1 9% Test 2 9% Test 3 9% Final 25% Homework 20% Lab 10% Part./Quiz 11% Project 7% Grade Assigned 93% A 73% C 90% A- 70% C- 87% B+ 67% D+ 83% B 63% D 80% B- 60% D- 77% C+ <60% F Possibility of curving Do not allow extra credit

Background Information Prerequisites Physics: PHY 113 (or 111), mechanics, etc. You should have a good understanding of basic physics Be familiar with units and keeping track of them, scientific notation Should know key elementary formulas like F = ma Mathematics: MTH 111, introductory calculus Know how to perform derivatives of any function Understand definite and indefinite integration Work with vectors either abstractly or in coordinates There is a math review online with everything you need to know

Red boxes mean memorize this, not just here, but always! SI Units Red boxes mean memorize this, not just here, but always! Fundamental units Time (second) s Distance (meter) m Mass (kilogram) kg Temperature (Kelvin) K Charge (Coulomb) C Derived units Force (Newtons) N kgm/s2 Energy (Joule) J Nm Power (Watt) W J/s Frequency (Hertz) Hz s-1 Elec. Potential (Volt) V J/C Capacitance (Farad) F C/V Current (Ampere) A C/s Resistance (Ohm)  V/A Mag. Field (Tesla) T Ns/C/m Magnetic Flux (Weber) Wb Tm2 Inductance (Henry) H Vs/A Metric Prefixes 109 G Giga- 106 M Mega- 103 k kilo- 1 10-3 m milli- 10-6  micro- 10-9 n nano- 10-12 p pico- Check units! Quick example – Work, KE, PE

Vectors A scalar is a quantity that has a magnitude, but no direction Mass, time, temperature, distance In a book, denoted by math italic font A vector is a quantity that has both a magnitude and a direction Displacement, velocity, acceleration In books, usually denoted by bold face When written, usually draw an arrow over it In three dimensions, any vector can be described in terms of its components Denoted by a subscript x, y, z The magnitude of a vector is how long it is Denoted by absolute value symbol, or same variable in math italic font z y vx vz vy x

Finding Components of Vectors If we have a vector in two dimensions, it is pretty easy to compute its components from its magnitude and direction y v vy We can go the other way as well vx x In three dimensions it is harder

Unit Vectors We can make a unit vector out of any vector Denoted by putting a hat over the vector It points in the same direction as the original vector The unit vectors in the x-, y- and z-direction are very useful – they are given their own names i-hat, j-hat, and k-hat respectively Often convenient to write arbitrary vector in terms of these

Adding and Subtracting Vectors To graphically add two vectors, just connect them head to tail To add them in components, just add each component Subtraction can be done the same way

Multiplying Vectors There are two ways to multiply two vectors The dot product produces a scalar quantity It has no direction It can be pretty easily computed from geometry It can be easily computed from components The cross product produces a vector quantity It is perpendicular to both vectors Requires the right-hand rule Its magnitude can be easily computed from geometry It is a bit of a pain to compute from components

Electricity q b a s r  z 50 kV Dirty air Cleanair + -

Electricity Electric Fields Electric Charge Electric forces affect only objects with charge Charge is measured in Coulombs (C). A Coulomb is a lot of charge Charge comes in both positive and negative amounts Charge is conserved – it can neither be created nor destroyed Charge is usually denoted by q or Q There is a fundamental charge, called e All elementary particles have charges that are simple multiples of e Particle q Proton e Neutron 0 Electron -e Oxygen nuc. 8e ++ 2e Red dashed line means you should be able to use this on a test, but you needn’t memorize it

Charge Can Be Spread Out Charge may be at a point, on a line, on a surface, or throughout a volume Linear charge density  units C/m Multiply by length Surface charge density units C/m2 Multiply by area Charge density units C/m3 Multiply by volume

Concept Question A box of dimensions 2 cm 2 cm  1 cm has charge density  = 5.0 C/cm3 throughout and linear charge density  = – 3.0 C/cm along one long diagonal. What is the total charge? A) 2 C B) 5 C C) 11 C D) 29 C E) None of the above – 3.0 C/cm 2 cm 5.0 C/cm3 1 cm 2 cm

The Nature of Matter Matter consists of positive and negative charges in very large quantities There are nuclei with positive charges Surrounded by a “sea” of negatively charged electrons + To charge an object, you can add some charge to the object, or remove some charge But normally only a very small fraction 10-12 of the total charge, or less Electric forces are what hold things together But complicated by quantum mechanics Some materials let charges move long distances, others do not Normally it is electrons that do the moving Insulators only let their charges move a very short distance Conductors allow their charges to move a very long distance

Some ways to charge objects By rubbing them together Not well understood By chemical reactions This is how batteries work By moving conductors in a magnetic field Get to this in October By connecting them to conductors that have charge already That’s how outlets work Charging by induction Bring a charge near an extended conductor Charges move in response Separate the conductors Remove the charge – + – + +

Coulomb’s Law Like charges repel, and unlike charges attract The force is proportional to the charges It depends on distance q1 q2 Other ways of writing this formula The r-hat just tells you the direction of the force When working with components, often helps to rewrite the r-hat Sometimes this formula is written in terms of a quantity0 called the permittivity of free space