Course overview
Physics 122, Fall 2013
9/3/13
Lecture I
1
Introduction
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Instructor Prof. Regina Demina Office B&L 367 Phone 275-7357
Email [email protected] Office hour Mon 3-4 pm
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Novosibirsk
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Objective of the course
•  thorough understanding of the basic physics
concepts
•  ability to use them in applications
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Sources
•  Text book
Physics for Scientists and Engineers, Volume II
Forth Edition
by Douglas C. Giancoli
• Class web site /www.pas.rochester.edu/~regina/PHY122
• Lecture notes;
• Homework assignments
• Workshop modules
• Equation sheets for tests, test solutions
• Important dates and links
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Workshops and Homework
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Solving problems systematically is important.
Peer-lead study groups – workshops
Workshops start next week
Participation in workshops = 5% of your final grade, need to
participate (not just attend!) in at least 10 workshops to get full
grade. •  Homework problems are similar but not identical to workshop
modules
•  Homework problems = 5% of your final grade.
•  Questions on workshop scheduling:
"Ryan Waldman" <[email protected]>
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Midterm exams
•  There will be three midterm exams during the
semester.
•  Two best will count. •  There will be no makeup exam. •  You can bring a calculator, a pencil and a ruler.
•  40% of your grade.
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Final Exam
•  December 18, 7:15 pm
•  Final exam is based on the entire course PHY122. •  Last homework will be based on the entire course to give you
more time to prepare for the final. •  40% of the final grade
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Lecture I
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Equation sheets
•  No notes or equation sheets may be brought to
exams. •  However, a sheet of useful equations will be
provided during the test. You can view these
sheets in advance, will be linked from course
schedule on the web.
•  Please note that past experience has shown that
having equations available does not guarantee
success -- understanding is the key.
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Lecture I
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Labs
•  The laboratory is a required and integrated part of the course. •  A passing grade in laboratory is required to pass the course: 10%
of the grade •  Questions should go to [email protected]
•  NB. I am not allowed to reveal this person’s identity.
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Grading
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Workshops:
Homework:
Hour Exams:
Final Exam:
Laboratory:
Total:
90% or above:
80% - 85% :
70% - 75%:
60% - 65%:
•  Under 60% :
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A
B
C
D
88-89.9 – A
78-79.9 – B
68-69.9 – C
E
5%
5% 40% 40% 10% 100%
85-87.9 – B+
75-77.9 – C+ 65-67.9 – D+
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PHY122 too easy?
You still have a chance to
switch to PHY142
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How to study for physics class
•  Look through lecture notes first
–  In lectures I’ll give you all the information that you need to
survive in this class
•  Read the suggested sections from the text book
–  Read the summary first – concentrate on what’s important
–  Don’t overdo the reading part, try to understand not
memorize
–  Pay attention to
•  Figures, spend more time on them than on text
•  Examples, try to work out the problem yourself first
•  Equations (try to analyze, e.g. if the charge doubles the Coulomb force
on it will double as well)
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Lecture I
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How to do physics problems
•  Use the “How to do physics problems” guide
posted on the course web site
•  While doing first several homework assignments
and workshop modules stick to it religiously
•  This practice will help you during the tests
•  PHY122 is a lot more abstract than PHY121 –
well developed procedures will help you to get
started
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PHY 121
•  Kinematics – how do objects move?
–  Trajectory, displacement, velocity, acceleration, time
•  Dynamics – why do objects move?
–  Mass, forceè work
–  Conserved quantities
•  Energy – potential and kinetic
•  Momentum
•  First step into micro world – kinetic theory
–  Mechanical laws work on molecules
–  Heat is a form of energy
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PHY 122
•  What is the origin of forces?
–  So far we considered only one true force – gravity
–  Next step – electricity and magnetism
•  Static – new conserving quantity – electric charge
•  Dynamic – DC and AC
•  Magnetic field
•  Electromagnetic waves – light
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Phases of matter
•  Solid,
liquid,
gas
Matter is built of atoms
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Inside atoms
•  Atoms have structure = nucleus +
electrons
•  Nucleus has positive electric
charge
•  Electron has negative electric
charge
•  Nucleus has structure = protons
and neutrons
•  Electron so far is believed to be
elementary = unbreakable
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Lecture I
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My research - LHC
Alps
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•  Large Hadron Collider located in Europe (France and
Switzerland)
•  Circumference 27 km;
•  7TeV(2010-2011)à8TeV (now)à14 Tev(2014)
•  LHC has uncovered the mechanism behind mass - 2012
•  Discovery of particle known as Higgs boson
•  Prof Hagen (Rochester) – one of the six people who
predicted this mechanism
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Hàγγ
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Lecture XII
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HàΖΖ*à4l
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Electricity
•  There are two kinds of
electric charges – positive
and negative.
•  Like charges
(++, or --) repel,
•  unlike charges (+-)
attract.
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Inside atoms
•  Atoms have structure =
nucleus + electrons
•  Nucleus has positive electric
charge
•  Electron has negative
electric charge (Q= -e)
•  Nucleus =
protons (Q=+e) and
neutrons (Q=0)
Electrons are much lighter and
thus more mobile than
protons or neutrons.
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Electric charge
•  The net charge is conserved.
•  Electric charge is measured in Coulombs.
•  Electron has negative charge (e=-1.60.10-19 C),
nucleus – positive.
•  Atom is electrically neutral.
•  Nucleus is heavy, electron is light. Usually charge is
transported by electrons.
•  By acquiring more electrons bodies become
negatively charged (Q= -Ne .e)
•  By loosing electrons bodies become positively
charged (Q= +Ne .e).
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Insulators and conductors
•  In solids atoms and their
nuclei are “locked” in their
position and hard to move.
•  Insulators have complete or
almost complete electron
shells – these electrons are
tough to move around.
•  Conductors (usually metals)
have one or two electrons
on the outer shell – “free”
electrons.
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Induced charge
Bodies can be charged by
•  Conduction (direct
contact)
•  Induction – create charge
separation
–  Break into pieces
–  “Ground“ one end – charge
leaks into the Earth.
Always think, where
electrons went –
they are the ones to move.
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Electroscope
Electroscope – a simple
device to detect electric
charge.
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Test problem #1
•  Two electrically neutral materials are rubbed
together. One acquires a net positive charge.
The other must
–  A
–  B
–  C
–  D
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have lost electrons.
have gained electrons.
have lost protons.
have gained protons.
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Coulomb’s law
•  F – force between two charges(N)
Q1Q2
F =k 2
•  Q – electric charge (C= Coulomb)
r
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2
2 •  r – distance between the two
k = 9.0 ⋅10 Nm / C
F12
+
1
+
F12
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+
F21
2
F21
2
charges (m)
•  k – constant
1 Q1Q2
F=
4πε 0 r 2
ε 0 = 8.85 ⋅10 −12 C 2 / Nm 2
ε 0 − permittivity of free space
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This week
•  Sign up for workshops if you have not done so.
•  Workshops start next week.
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