1. Coulomb’s Stuff

2. More on problem solving & Quizzes/exams
When possible, use words to state what your plan of attack is.
Also when possible, try to formulate problems using algebraic symbols rather than starting with a page full of numbers.
Generally, if your work can’t be followed, it will be graded as incorrect.
Always be sure to append units to every answer.
Write as neatly as you possibly can.

3. Grader Instructions.
Papers should be returned to the instructor within one week of the quiz/exam.
If no solution is offered by the instructor and there are questions, please ASK for the solution before grading begins if you need it.
Quizzes are to be graded on a scale of 1 to 10.
When points are removed, the student should see an indication as to the reason for the reduction.
The presentation from the student should be CLEAR.  If it is not, up to 2 points may be deducted.
Grading should not be harsh.  But it should be accurate.
If a result is a vector, the magnitude and direction as well as the units should be present.
If a result is obtained algebraically and is correct, any arithmetic errors should not result in a loss of more than 1 point.  If the algebra is incorrect, no points can be awarded.
Answers without any work being shown should be graded as a zero.

4. Last time we discussed coulomb’s law
k and e0 are fundamental constants
F is a VECTOR QUANTITY
The direction of F is always along the line connecting the two charges
+ sign indicates repulsion; - sign, attractive
Use superposition to add forces .. one charge at a time.

5. QUIZ TIME This is an INDIVIDUAL quiz.
Be sure your name is on the paper.

6. What is the DIRECTION
of the force on B due to the
charges at A and C?
A – UP
B – DOWN
C – LEFT
D – RIGHT
E - OTHER

7. The Quiz
Then you put
the numbers in

9. The Real Deal

10. MEAN! This is WAR Ming the merciless this guy is
You are fighting the enemy on the planet Mongo.
The evil emperor Ming’s forces are behind a strange green haze.
You aim your blaster and fire … but ……

11. Nothing Happens! The Green thing is a Force Field!
The Force may not be with you ….

12. Side View
The
FORCE FIELD
Force
|Force|
Big! o
Position

13. Properties of a FORCE FIELD
It is a property of the position in space.
There is a cause but that cause may not be known.
The force on an object is usually proportional to some property of an object which is placed into the field.

14. Begin the next
exercise:
The Electric Field