PHYS 1444 – Section 003 Lecture #2

PHYS 1444 – Section 003 Lecture #2
Tuesday, Aug. 30, 2011 Dr. Jaehoon Yu Some basics … Chapter 21 Static Electricity and Charge Conservation Charges in Atom Today’s homework is homework #2, due 10pm, Tuesday, Sept. 6!! Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

PHYS 1444-003, Fall 2011 Dr. Jaehoon Yu
Announcements Plea to you: Please turn off your cell-phones, pagers and computers in the class Reading assignment #1: Read and follow through all sections in appendix A by Tuesday, Aug. 30 A-1 through A-7 There will be a quiz on this and Ch. 21 on Thursday, Sept. 1. Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

Who am I? Name: Dr. Jaehoon Yu (You can call me Dr. Yu) Office: Rm 342, Chemistry and Physics Building Extension: x22814, My profession: High Energy Particle Physics (HEP) Collide particles (protons on anti-protons or electrons on anti-electrons, positrons) at the energies equivalent to 10,000 Trillion degrees To understand Fundamental constituents of matter Forces between the constituents (gravitational, electro-magnetic, weak and strong forces) Origin of Mass Creation of Universe (Big Bang Theory) A pure scientific research activity Direct use of the fundamental laws we find may take longer than we want but Indirect product of research contribute to every day lives; eg. WWW Why do we do with this? Make our everyday lives better Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

Accelerators are Powerful Microscopes.
They make high energy particle beams that allow us to see small things. seen by low energy beam (poorer resolution) seen by high energy beam (better resolution) Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

E = mc2 Accelerators are also Time Machines.
They make particles last seen in the earliest moments of the universe. Energy particle beam energy anti-particle beam energy Particle and anti-particle annihilate. E = mc2 Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

Structure of Matter Matter Molecule Atom Nucleus High Energy Physics Baryon (Hadron) u Quark 10-2m 10-9m 10-10m 10-14m 10-15m <10-19m Condensed matter/Nano-Science/Chemistry protons, neutrons, mesons, etc. p,W,L... top, bottom, charm, strange, up, down Atomic Physics Nuclear Physics Electron (Lepton) <10-18m Give scale and relationship to the domain that high energy physicists work in. Introduce the fundamental bits of matter loosely so that audience can point back to bulk matter. Domain. Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

The Standard Model Assumes the following fundamental structure: Discovered in 1995 Directly observed in 2000 Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

Fermilab Tevatron and LHC at CERN
World’s Highest Energy p-p collider 27km circumference, 100m underground Design Ecm=14 TeV (=44x10-7J/p 362M Joules on the area less than 10-4m2) Equivalent to the kinetic energy of a B727 (80tons) at the speed 193mi/hr  312km/hr ~3M times the energy density at ground 0 of atom bomb dropped on Hiroshima First 7TeV collisions on 3/30/10  The highest energy humans ever achieved!! First collisions in 2011 in mid March, 2011 World’s Highest Energy proton-anti-proton collider 6km circumference Ecm=1.96 TeV (=6.3x10-7J/p 13M Joules on 10-4m2) Equivalent to the kinetic energy of a 20t truck at the speed 81mi/hr 130km/hr ~100,000 times the energy density at ground 0 of the atom bomb dropped on Hiroshima To be shut down Sept. 30, 2011 Chicago Tevatron p CDF DØ Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

A Future Linear Collider
An electron-positron collider on a straight line for precision measurements CMS Energy: 0.5 – 1 TeV 10~15 years from now Takes 10 years to build the accelerator and the detector L~31km Circumference ~6.6km ~300 soccer fields Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

DØ Detector ATLAS Detector 30’ 50’ Weighs 7000 tons and 10 story tall Can inspect 1,000,000,000 collisions/second Records 200 – 400 collisions/second Records approximately 350,000,000 bytes/second Record 2x1015 (2,000,000,000,000,000) bytes each year (2 PetaByte).  200*Printed material of the US Lib. of Congress Weighs tons and 5 story tall Can inspect 3,000,000 collisions/second Record 100 collisions/second Records approximately 10,000,000 bytes/second Records 0.5x1015 (500,000,000,000,000) bytes per year (0.5 PetaBytes). Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

DØ Central Calorimeter 1990
Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

Computers put together a picture
Digital data p `p Data Reconstruction Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

How does an Event Look in a Collider Detector?
Time “parton jet” “particle jet” “calorimeter jet” hadrons  CH FH EM Highest ET dijet event at DØ RECO [Slide 1] Very briefly mention RECO version used. Mention that these are fixed-cone jets of R=0.7 found by iterative algorithm, Et is the scalar Et sum of the towers. List corrections we apply (basically) to RECO. No more is needed for AIDA restoration or Ht-revertexing at this point, but following three slides will be about eta bias -- so just briefly prepare listeners for this! Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

GEM Application Potential
FAST X-RAY IMAGING Using the lower GEM signal, the readout can be self-triggered with energy discrimination: 9 keV absorption radiography of a small mammal (image size ~ 60 x 30 mm2) A. Bressan et al, Nucl. Instr. and Meth. A 425(1999)254 F. Sauli, Nucl. Instr. and Meth.A 461(2001)47 Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

Information & Communication Source
My web page: Contact information & Class Schedule Syllabus Homework Holidays and Exam days Evaluation Policy Class Style & Communication Other information Primary communication tool is Make sure that your address at the time of the registration is your most favorite primary one. Will send a test message this afternoon. Please reply just to “me” for confirmation of the communication. 3 point extra credit if done just to ME by 11pm Friday, tomorrow. Office Hours: 2:00 – 3:00pm, Tuesdays and Thursdays or by appointments Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

Evaluation Policy Homework: 25% Exams Midterm and Final Comprehensive Exams (10/20 and 12/15): 19% each One better of the two term Exams: 12% Total of two non-comprehensive term exams (9/29 and 11/22) One better of the two exams will be used for the final grade Missing an exam is not permissible unless pre-approved No makeup test You will get an F if you miss any of the exams without a prior approval Lab score: 15% Pop-quizzes: 10% Extra credits: 10% of the total Random attendances Physics department colloquium participation Strong participation in the class discussions Special projects Planetarium shows and Other many opportunities Grading will be done on a sliding scale 100% Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

Homework Solving homework problems is the only way to comprehend class material An electronic homework system has been setup for you Details are in the material distributed today and on the web Choose the course PHYS , unique number 44003 Download homework #1, solve the problems and submit them online Multiple unsuccessful tries will deduct points Roster will close Tuesday, Aug. 30 You need a UT e-ID: Go and apply at the URL if you don’t have one. Each homework carries the same weight ALL homework grades will be used for the final grade Home work will constitute 25% of the total  A good way of keeping your grades high Strongly encouraged to collaborate  Does not mean you can copy Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

Attendances and Class Style
Will be taken randomly Will be used for extra credits Class style: Lectures will be on electronic media The lecture notes will be posted on the web AFTER each class Will be mixed with traditional methods Active participation through questions and discussions are STRONGLY encouraged  Extra credit…. Communication between you and me is extremely important If you have problems, please do not hesitate talking to me Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

Lab and Physics Clinic Physics Labs: Starts Tuesday, Sept. 6 Important to understand physical principles through experiments 15% of the grade Lab syllabus is available in your assigned lab rooms. Go by the lab room between 8am - 6pm M – F and pick up the syllabus Physics Clinic: Free service They provide general help on physics, including help solving homework problems Do not expect solutions of the problem from them! Do not expect them to tell you whether your answers are correct! It is your responsibility to make sure that you have done everything correctly! 11am – 6pm, Mon – Fri and 12 – 6pm Sat. in SH 007 This service begins Thursday, Sept. 1 Addition help: Supplemental Instruction: Husain Lohawala 2:30 – 3:30pm, Mondays and Wednesdays in SH333 Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

Extra credit 10% addition to the total Could boost a B to A, C to B or D to C What constitute for extra credit? Random attendances Physics department colloquium participation Some will be double or triple credit ( Strong participation in the class discussions Special projects Watch the valid planetarium shows Many other opportunities Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

Valid Planetarium Shows
Regular running shows We are Astronomers Nanocam: Trip into Biodiversity Shows that need special arrangements Black Holes Ice Worlds Magnificent Sun Stars of the Pharaohs Time Space Two Small Pieces of Glass SOFIA Violent Universe How to submit for extra credit? Obtain the ticket stub that is signed and dated by the planetarium star lecturer of the day Collect the ticket stubs Tape all of them on a sheet of paper with your name and ID written on it Submit the sheet at the end of the semester when asked Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

What can you expect from this class?
All A’s? This would be really nice, wouldn’t it? But if it is too easy it is not fulfilling or meaningful…. This class is not going to be a stroll in the park!! You will earn your grade in this class. You will need to put in sufficient time and sincere efforts Exams and quizzes will be tough!! Sometimes problems might not look exactly like what you learned in the class Just putting the right answer in free response problems does not work! But you have a great control of your grade in your hands Homework is 25% of the total grade!! Means you will have many homework problems Sometimes much more than any other classes Sometimes homework problems will be something that you have yet to learn in class Exam’s problems will be easier that homework problems but same principles!! Lab 15% Extra credit 10% I will work with you so that your efforts are properly rewarded Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

What do we want to learn in this class?
Physics is everywhere around you. Skills to understand the fundamental principles that surrounds you in everyday lives… Skills to identify what laws of physics applies to what phenomena and use them appropriately Understand the impact of physical laws and apply them Learn skills to think, research and analyze observations. Learn skills to express observations and measurements in mathematical language Learn skills to express your research in systematic manner in writing But most importantly the confidence in your physics ability and to take on any challenges laid in front of you!! Most importantly, let us have a lot of FUN!! Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

In this course, you will learn…
Electricity and Magnetism Electric and Magnetic Forces Electric charge and magnetic poles Electric and magnetic potential and energies Propagation of electric and magnetic fields Relationship between electro-magnetic forces and light Behaviors of light and optics Special relativity and quantum theories Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

Brief History of Physics
AD 18th century: Newton’s Classical Mechanics: A theory of mechanics based on observations and measurements AD 19th Century: Electricity, Magnetism, and Thermodynamics Late AD 19th and early 20th century (Modern Physics Era) Einstein’s theory of relativity: Generalized theory of space, time, and energy (mechanics) Quantum Mechanics: Theory of atomic phenomena Physics has come very far, very fast, and is still progressing, yet we’ve got a long way to go What is matter made of? How do matters get mass? How and why do matters interact with each other? How is universe created? Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

Needs for Standards and Units
Three basic quantities for physical measurements Length, Mass, and Time Need a language that everyone can understand each other Consistency is crucial for physical measurements The same quantity measured by one must be comprehendible and reproducible by others Practical matters contribute A system of unit called SI (System International) established in 1960 Length in meters (m) Mass in kilo-grams (kg) Time in seconds (s) Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

SI Base Quantities and Units
Quantity Unit Unit Abbrevation Length Meter m Time Second s Mass Kilogram kg Electric current Ampere A Temperature Kelvin k Amount of substance Mole mol Luminous Intensity Candela cd There are prefixes that scales the units larger or smaller for convenience (see pg. 7) Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

Prefixes, expressions and their meanings
deca (da): 101 hecto (h): 102 kilo (k): 103 mega (M): 106 giga (G): 109 tera (T): 1012 peta (P): 1015 exa (E): 1018 deci (d): 10-1 centi (c): 10-2 milli (m): 10-3 micro (m): 10-6 nano (n): 10-9 pico (p): 10-12 femto (f): 10-15 atto (a): 10-18 Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

How do we convert quantities from one unit to another?
Conversion factor X Unit 2 1 inch 2.54 cm 0.0254 m 2.54x10-5 km 1 ft 30.3 0.303 M 3.03x10-4 1 hr 60 minutes 3600 seconds And many More Here…. Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

Static Electricity; Electric Charge and Its Conservation
Electricity is from Greek word elecktron=amber, a petrified tree resin that attracts matter if rubbed Static Electricity: an amber effect An object becomes charged or “posses a net electric charge” due to rubbing Can you give some examples? Two types of electric charge Like charges repel while unlike charges attract Benjamin Franklin referred the charge on glass rod as the positive, arbitrarily. Thus the charge that attracts glass rod is negative.  This convention is still used. Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

Static Electricity; Electric Charge and Its Conservation
Franklin argued that when a certain amount of charge is produced on one body in a process, an equal amount of opposite type of charge is produced on another body. The positive and negative are treated algebraically so that during any process the net change in the amount of produced charge is 0. When you comb your hair with a plastic comb, the comb acquires a negative charge and the hair an equal amount of positive charge. This is the law of conservation of electric charge. The net amount of electric charge produced in any process is ZERO!! If one object or one region of space acquires a positive charge, then an equal amount of negative charge will be found in neighboring areas or objects. No violations have ever been observed. This conservation law is as firmly established as that of energy or momentum. Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

Electric Charge in the Atom
It has been understood through the past century that an atom consists of A positively charged heavy core  What is the name? This core is nucleus and consists of neutrons and protons. Many negatively charged light particles surround the core  What is the name of these light particles? These are called electrons How many of these? So what is the net electrical charge of an atom? Zero!!! Electrically neutral!!! Can you explain what happens when a comb is rubbed on a towel? Electrons from towel get transferred to the comb, making the comb negatively charged while leaving positive ions on the towel. These charges eventually get neutralized primarily by water molecules in the air. As many as the number of protons!! Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

Insulators and Conductors
Let’s imagine two metal balls of which one is charged What will happen if they are connected by A metallic object? Some charge is transferred. These objects are called conductors of electricity. A wooden object? No charge is transferred These objects are called nonconductors or insulators. Metals are generally good conductors whereas most other materials are insulators. There are third kind of materials called, semi-conductors, like silicon or germanium  conduct only in certain conditions Atomically, conductors have loosely bound electrons while insulators have them tightly bound! Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

Induced Charge When a positively charged metal object is brought close to an uncharged metal object If the objects touch each other, the free electrons in the neutral ones are attracted to the positively charged object and some will pass over to it, leaving the neutral object positively charged. If the objects get close, the free electrons in the neutral ones still move within the metal toward the charged object leaving the opposite of the object positively charged. The charges have been “induced” in the opposite ends of the object. Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

Induced Charge ground We can induce a net charge on a metal object by connecting a wire to the ground. The object is “grounded” or “earthed”. Since it is so large and conducts, the Earth can give or accept charge. The Earth acts as a reservoir for charge. If the negative charge is brought close to a neutral metal The positive charges will be induced toward the negatively charged metal. The negative charges in the neutral metal will be gathered on the opposite side, transferring through the wire to the Earth. If the wire is cut, the metal bar has net positive charge. An electroscope is a device that can be used for detecting charge and signs. How does this work? Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

Coulomb’s Law Charges exert force to each other. What factors affect the magnitude of this force? Any guesses? Charles Coulomb figured this out in 1780’s. Coulomb found that the electrical force is Proportional to the multiplication of the two charges If one of the charges doubles, the force doubles. If both the charges double, the force quadruples. Inversely proportional to the square of the distances between them. Electric charge is a fundamental property of matter, just like mass. How would you put the above into a formula? Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

Coulomb’s Law – The Formula
Is Coulomb force a scalar quantity or a vector quantity? Unit? A vector quantity. Newtons Direction of electric (Coulomb) force is always along the line joining the two objects. If the two charges are the same: forces are directed away from each other. If the two charges are opposite: forces are directed toward each other. Coulomb force is precise to 1 part in 1016. Unit of charge is called Coulomb, C, in SI. The value of the proportionality constant, k, in SI unit is Thus, 1C is the charge that gives F~9x109N of force when placed 1m apart from each other. Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

and Gravitational Force
Electric Force and Gravitational Force Extremely Similar Does the electric force look similar to another force? What is it? Gravitational Force What are the sources of the forces? Electric Force: Charges, fundamental properties of matter Gravitational Force: Masses, fundamental properties of matter What else is similar? Inversely proportional to the square of the distance between the sources of the force  What is this kind law called? Inverse Square Law What is the difference? Gravitational force is always attractive. Electric force depends on the type of the two charges. Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

The Elementary Charge and Permittivity
Elementary charge, the smallest charge, is that of an electron: Since electron is a negatively charged particle, its charge is –e. Object cannot gain or lose fraction of an electron. Electric charge is quantized. It changes always in integer multiples of e. The proportionality constant k is often written in terms of another constant, e0, the permittivity of free space. They are related and Thus the electric force can be written: Note that this force is for “point” charges at rest. Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

Example 21 – 1 Electric force on electron by proton. Determine the magnitude of the electric force on the electron of a hydrogen atom exerted by the single proton (Q2=+e) that is its nucleus. Assume the electron “orbits” the proton at its average distance of r=0.53x10-10m. Using Coulomb’s law Each charge is and So the magnitude of the force is Which direction? Toward each other… Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

Example 21 – 2 Which charge exerts greater force? Two positive point charges, Q1=50mC and Q2=1mC, are separated by a distance L. Which is larger in magnitude, the force that Q1 exerts on Q2 or the force that Q2 exerts on Q1? What is the force that Q1 exerts on Q2? What is the force that Q2 exerts on Q1? Therefore the magnitudes of the two forces are identical!! Well then what is different? The direction. Which direction? Opposite to each other! What is this law? Newton’s third law, the law of action and reaction!! Thursday, Aug. 25, 2011 PHYS , Fall 2011 Dr. Jaehoon Yu

PHYS 1444 – Section 003 Lecture #2

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