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## Table of Contents

## Videos:

## Coulomb's Law

## Right Hand Rule:

## Labs:

## Lab 1

## Lab 2

Lab 3

Do lab 2 instead of 3.

Lab 4

## Notes:

When you are given diagrams on this unit, you have to draw a force diagram most of the time.When the question asks for the force, you have to report your answer with the appropriate sign.

If the question asks for the "magnitude" of the force, your answer will be the numeric answer with no sign.

*Find the equilibrium Distance:*Resolution Force between Three or More Point ChargesWhen you connect two sphere’s with a wire the two currents in coulombs are averaged. Then calculate the Force electric using the regular formula for Fe.## Discussion:

re: Electric Fields**nchshadenj** Jan 21, 2010 7:12 am

In the Electric Fields section the number one rule to remember is "opposites attract and likes repel." Nearly all of the problems in the packet use the formulas from Chapter 17 in the book. Use diagrams and force vectors to make it easier to visualize the problem. The labs from the Electric Fields section are fairly simple and the questions that go along with them are just extensions from the work packet.

Haden J

**andreashaycumberland** Jan 21, 2010 7:19 am

Always read the problem to make sure which Coulumb constant it gives 8.99x10^9 or 8.98755x10^9 or it will mess the answer up when u try to answer on homework quest.

There's a chart on page 630 that gives the charges and masses of protons and neutrons.

The labs are pretty simple they just explain and better show you how electric fields look around charges.

**ethanp1** Mar 26, 2010 7:13 am

For electric fields your two main formulas are Felec=Kc(q1*q2)/d^2 and Efield=Kc(q/d^2) also you may use F=Eq once or twice. if you have several charges remember to use Sine Cosine and Tangent to resolve the multiple forces.

**nchsclarkm** Mar 30, 2010 7:18 am

To Whom It May Concern:

Electric fields has been admitted by Mrs. Duncan as the most difficult section in the book. There are only 20 or so problems, but they are very difficult and it’s best not to skip around. Some things to make a note of is that you always make sure to check the value of the Coulomb constant (kC) for each problem. Sometimes it’s a longer number and others it is rounded to just 8.99e9. This will affect your answer if you don't keep an eye on it. Whenever you get to the problems about having points on an axis, make sure you put them on the correct planes. There are usually two points on an x-axis and one on the y or vice-versa. You have to draw triangles with these so you can figure out the missing data with sine, cosine, and tangent.

Good luck,

Michael Clark

**abbycatheryn** Apr 14, 2010 7:25 am

-Draw all diagrams! If you don’t it will be extremely hard!

-When drawing diagrams and adding vectors it’s very important to label the positive and negative charges so you will know which way the vectors will go

-When you are trying to figure out if the electric force is on the positive or negative x-axis read page 643

Good luck!

**amr3363** Apr 14, 2010 7:26 am

Do not be fooled by the number of problems in this chapter. Chapter 17 is very difficult. I suggest reading the entire chapter before beginning. Go ahead and WRITE DOWN all of your formulas so you can have them handy. You will have to use the protons and electrons, too. There are two that you will have to use factor label on. Just think it through, make sure you change micro Coulumbs to Coulumbs by adding e-6. Don't procrastinate!! Use all the time you have wisely. The labs were the easiest thing about this chapter. Read each problem carefully, consider what it's asking, and THEN try it. Also, there are a lot of sample problems in the book that you can follow along with. You're going to have to use your trig functions with sine, cosine, and tangent. BE CAREFUL!!!!

Ashley Rentz

SLovornNCHS

Jan 19, 2012 10:47 pm

To those AP Physics students reading this, like Mrs. Duncan said, this is one of the hardest rotations you will face...to get started, but this rotation is very repetitive in that the problems basically adding vectors, which you already know how to do with 2 basic formulas thrown in. The 2 formulas are: Force=kC(q1q2)/r^2 and Electric Field=kC(q)/r^2 where in kC is the Coulomb constant, usually 8.98755x10^9 Nxm^2/C^2 or 8.99x10^9 Nxm^2/C^2, q is the charge of your point, and r is the distance between the 2 charges. If your answer is in N, then you will use the Force formula. If your answer is in N/C, the Electric Field formula will be used.

DRAW A DIAGRAM!!! That is the best advice you will receive. If it says 4 points arranged in a square, draw just that making sure to label each point as + or -. Remember, opposites attracts and likes repel. Draw lines representing the forces either repelling each other or being attracted to each other. After you have found the force or field of the point, you will already have direction.

There were questions I found that were simple vector problems that asked you to find the net electric force of a certain point exerted by other points upon it. After that, you'll be asked to find the direction, or degrees, in which the force is being applied. If the degrees problem asks for an angle between -180 degrees and 180 degrees, it means that once the new triangle has been drawn, after adding your vectors together, you will come out with a + or - angle. You can have a - angle. Remember that the positive x-axis is 0 degrees and counterclockwise position is + while clockwise position is -. You will also have to subtract the angle you found from 180 to find your final angle which means your angle will be larger than 90 degrees so don't panic.

One last thing; C stands for Coulombs but uC (micro coulombs) is Cx10^-6 and nC (nano coulombs) is Cx10^-9.

-Sam Lovorn