PHYSICS 1E03
Dr. W. Okoń
Office: ABB-150
e-mail: okon@physics.mcmaster.ca
Office Hours: TBA
Course web page (all sections) – Course Outline:
http://physwww.mcmaster.ca/PHYS1E03
Course web page – I will be posting news and all lecture
notes here:
http://physwww.mcmaster.ca/~okon/1e03/1e03.html
Components of the course
-Lectures: three per week
-Labs: approximately every second week, 4 labs in
the term. 15% of the final grade.
-Tutorials: approximately every second week,
alternating with labs. 6% of the final grade.
-CAPA assignments, every week. 23% of the final
grade
-Two term tests. Total 20% of the final grade.
-Final exam, 3 hours. 51-56% of the final grade.
- i-Clicker participation 5%
Missed Work Forms (MSAF)
For missed tutorials and midterm tests – Follow instructions on our site!
*When you use the MSAF form, the weight of the missed item is always
added to the final examination.
*The mark on Avenue will eventually show up as "-2" if I received the
form, but this may take up to a week as the forms need to be processed.
*E-mail me ONLY if your mark does not show as "-2" after about a week
after you submitted the form.
*DO NOT fill out an MSAF form for missed class attendance or CAPA –
these will be ignored/deleted and you will loose one form.
Homework Using CAPA
• There will be a CAPA assignment each week. Answers are entered
into the computer The CAPA system tells you immediately whether
the answer is correct, and allows you to try again. You can log
on/off and keep working on an assignment as often as you like.
•The CAPA assignments themselves are worth 3% of your grade;
and the tutorial quizzes are based on the same problems.
•You will get access to the CAPA assignments directly from Avenue.
This is simpler than the procedure for other courses that use CAPA,
but it means you have to get your Avenue login working
(http://avenue.mcmaster.ca/)
•Read the CAPA help page before you start!
Homework
Download and print the lecture notes in Power Point format from
the my web page. Bring the notes for class and add your own
notes to them during the lecture. Read the textbook, either just
before or just after the lecture, and add to your notes as you
read.
We will prepare a list of suggested problems from the textbook
(posted as a file, or at the end of lectures notes).
You can download and print these. As we cover the material
from the textbook you should also try to do the appropriate
questions from this list.
PHYSICS 1E03
I. Electrostatics
(4 weeks)
II. DC Circuits (2 weeks, plus labs)
III. Magnetism (3 weeks)
IV. Waves (3 weeks)
-includes electromagnetic waves
Introduction
How do things interact?
1) Gravity
- a force between masses
- holds planets in orbit, etc.
2) Electromagnetism
- a force between charges
- responsible for all familiar forces (except
gravity) – friction, normal, magnetic
3) Weak Nuclear Force
- decay of particles
4) Strong Nuclear Force
- holds nuclei together
Electric Charge
• A scalar quantity
• Comes in “positive” and “negative”
+
REPEL
-
-

F REPEL
+
-
+

F
ATTRACT
Units: coulomb, C
and also “smallest unit of charge”, e  1.60210-19 C
Electric Charge (continued)
• Charge appears in nature in units of “e”:
eg: Particle
electron
proton
Charge
-e
+e
•Net charge is a conserved quantity: that is,
the algebraic sum of positive and negative charges
is constant.
Eg +5e-3e = +2e = +8e-6e
Insulators: charges do NOT move
eg: glass, rubber, paper
- can be charged by rubbing,
but charges do not move
Conductors: (some) charges move freely
eg: metals, some liquids
Semiconductors: electrical properties
between insulators and
conductors
eg: silicon, germanium
Quiz
The conductor is neutral
(no net charge). When a
charged rod is brought
close to it (without
touching) the net force on
the conductor will be:
A)
B)
C)
D)
attractive
repulsive
zero
it depends whether the rod
is positive or negative
-----Conductor
Coulomb’s Law
Point charges q1, q2 exert forces on each other:

r
q1
F21
q2
F12
rˆ
qq
F k
rˆ
r
1
12
e
2
2
r̂ is a unit vector parallel to r
2
m
ke  8.988x 10 N 
9
C
2
(Coulomb’s constant)
Exercise:
Find the magnitude of the force between the
charges +10 C and -5 C separated by 20 cm.
Exercise:
L
GIVEN:
•Identical Masses, m=1.0 gram
L
30 30
m
q
(equilibrium)
m
q
•Equal charges q
•L= 60 cm
FIND: q
Quiz:
L
m
2q
?
? L
(equilibrium)
m
q/2
What happens to each angle if
the charge on the left is
doubled, and the other one is
halved? Assume mass of
charges is small.
A) angle increases
B) angle decreases
C) angle stays the same
Finding Resultant force vector:
q  20C
2
q  40  C
4
300mm
400mm
q3  30C
q1  10C
Find: Force (vector) on q3 , in Cartesian form.
Solution