Physics For Engineers and Scientists II

Principles of Electricity and Magnetism

Dr. Jeffrey B. Bindell

Fall 2005

Instructor: Dr. Jeffrey BindellSchedule M,W,F 10:30 AM to 11:20 AM Room 359

Phone 407-823-4194E-mail: bindell@physics.ucf.edu

Website: www.physics.ucf.edu/~physicsOFFICE HOURS: M,W,F 8:30-10:00 AM

MAP-417

General Information

Books and Stuff

Textbook Fundamentals of Physics Halliday, Resnick and Walker, Seventh Edition, Wiley

WebAssign Login

Keep in Mind

Grades

Item Weight

Mid Semester Examinations 3

Final Examination 2

Homework 2

In Class Quizzes 1

Homework

It is important to notice that homework counts for 25% of your grade. Homeworks will be based on WebAssign. Although “extensions” will be available, valid reasons should be offered at the time or he request.

There will be approximately two assignments per week. The first will be due on Monday and will require that some advance reading be done. These questions will be multiple choice. This will assure that you are properly prepared for the lecture and/or demonstration for the upcoming week. The second will be a series of more difficult problems and will generally be due on Fridays.

WebAssign Startup

Digits of your PID

ihatephysics

Be sure to change yourpassword as soon as possible to avoid someoneelse doing your homework!

No CurveSCORE GRADE85-100 A75-84 B60-74 C50-59 D

Less than 50 F

Approximate Exam Schedule

EXAM NUMBER

DATE

1 9-23 (Fri)

2 10-21 (Fri)

4 11-23 (Wed)

FINAL EXAMCheck UCF

Cal.

ratemyprofessors.com

Completely unforgiving. Unhelpful office hours from which you leave more confused and with more questions than you came with. Seems to have no time for students, will not listen to any excuse, reasonable or not. Do not be 1 minute late on quiz day. Family emergency, car trouble= unforgivable sin

Very difficult. Not in a tough way, but in an unhelpful way. Does not go over problems and his office hours are not helpful at all. You leave just as confused. Does not go over tests. 

ratemyprofessors.com

Waiting for grades to come in. Have no idea if I passes or failed. Tests are UNFAIR, GRADING IS UNFAIR. I didn't miss more than a day of class. This class is an experiment and I don't like being the guinea pig when my GPA is on the line. Something better give or EVERYONE in the class will fail. 

ratemyprofessors.com

This class sucks, but Bindell makes it doable. He answers ?'s, speaks clearly, and is pretty funny too. Fair tests and decent curves for the final grade. Do your webassign and make yourself known, you will pass this class... 

Very hard class.Tests consist of 1 homework problem and 2 unseen problems, one easy, one hard.If you go to office hours(if you can get him on a day he's there)he will usually give you extra points on tests that TA's graded unfairly. He also curves the grades a lot.I was looking at a C and made an A 

Comments from Surveys (abbreviated)

Powerpoint lectures suck! Too much, too fast. Too fast.

Do more problems in class and not as much theory.

Miss too many office hours. Last semester was bad. I will still miss some of them.

Missed too many classes. Indeed I did.

The Facts …

Last Semesters Final Grades

0

10

20

30

40

Grade

Per

cent

of C

lass

A B C D

F

F includes people who forgot to withdraw and just stopped attending.

What I learned:

Students don’t like lectures, especially PowerPoint.

Students don’t like WebAssign Some problems too hard Some problems are not coded correctly by WA.

Students don’t like tests unless they are easy. They’re NOT! Course is hard, why would tests be easy???

My gripes ….Students study at the last minute.Students have big holes in their math skills:

Interpreting Graphs. Using Calculus.

Students come to my office expecting me to solve their homework problems. I will always help … I will not give you the

answers! Work on the problems before you come for help.

Feedback Based Approach

More demos when possible.More problems in classMinimize PowerPoint.

Last semesters PP notes are on my website. Watch out for some errors that were not corrected on the slides.

This approach requires that class does its reading beforehand.

How to get an A.

Weekend Read next weeks material. Complete short answer assignment before class time.

During Week Work the long problems from WebAssign Different problems will be worked in class. Ask Questions

Fridays will usually be Quiz day unless you want them on Mondays. Some will be “strange”.

All exams will be on Fridays (except for the Wednesday before Thanksgiving) Studying helps!!

What’s Up?????

Today Introductory Comments Electricity (Read First Chapter on Charge)

Wednesday Electrical Forces and Problems

Friday Quiz Finish the Chapter

Basics of Electrical Charge

Week-1

Probable First Observation of Charge

Don’t Mess With Mother NatureSt. Elmo’s Fire

Top of Mast

A Quick Experiment

Idiot!

If lightening had actually traveled down the kite string, old Ben Franklin would have been toast!

History

600 BC Thales of Miletos rubs amber (electron in

Greek) with cat fur and uses it to pick up feathers.

Important questions: Why was he doing this? Didn’t he have a job?? What happened to the skinned cat?

Amber

Million years ago large stands of forests in some parts of the world began to seep globs of sticky resin! This aromatic resin oozed down the sides of trees, as well as filling internal fissures, trapping debris, such as seeds, leaves, feathers and insects. As geologic time progressed the forests were buried and the resin hardened into a soft, warm, golden gem, known as amber. Amber is the fossilized resin of ancient trees which forms through a natural polymerization of the original organic compounds. Most of the world's amber is in the range of 30-90 million years old.

Rubbings

Photo

Effect of Charge

What’s Going On?

All of these effects involve rubbing two surfaces together.

Or pulling two surfaces apart.Something is on each of these objects.We call this “something” CHARGE.

We have also observed that there must be TWO kinds of charge.

Call these two types positive (+) negative(-)

We “define” the charge that winds up on the rubber rod when rubbed by the dead cat to be NEGATIVE.

The charge on the glass rod or the dead cat is defined as POSITIVE.

What happens when two surfaces touch or rub?

Bonding!Bonding!

Example - Tape

The Triboelectric Series

No! No!

When two of the following materials are rubbed together under ordinary circumstances, the top listed material becomes positively charged and the lower listed material becomes

negatively charged.

MORE POSITIVE rabbit's fur

glass mica nylon wool

cat's fur silk

paper cotton wood

acrylic cellophane tape

polystyrene polyethylene

rubber balloon saran wrap

MORE NEGATIVE

No! No!

Summary - Rubbings

What have we found?

There are TWO types of charge. Positive Negative

Like Charges Attract Un-Like charges repel The force between charges increases as they

are brought closer together. This charge separation results from chemical

bonds which are severe in the pocess.

Forces Between Charges

Q1 Q2 Attract Repel

+ + X

+ - X

- + X

- - X

Types of MaterialsTypes of Materials

Insulators Holds a charge

Conductors Allows charge to easily move (current)

Semiconductors (Si, Ge, C …) Somewhere in the middle, very temperature and

impurity sensitive. Used for transistors and optical devices such as LEDs

and Semiconductor Lasers. Semi-Metals

Don’t ask!

The Electroscope