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Unformatted text preview: ISP209s7 Exam2 Review-1- Today Exam#2 Review Exam #2 is Thursday March 15 in this room, BPS 1410 Extra Credit Projects: Urban Legend and Spring Break Story Contest The exam is 40 multiple choice questions. There are a few questions where you will have to use a formula and calculator. Bring your student ID You will have the full 80 minutes for the exam. You can bring one 8.5x11 inch sheet of notes (front and back) ISP209s7 Exam2 Review-2- Where are we? There are 4 known forces in nature (Gravity, weak, EM- electromagnetic , strong) Gravity does not fit well in our understanding with the others It is very weak compared to the others. Why? Our current understanding of nature is by Quantum field theory: EM - quantum electrodynamics, EM+weak - electroweak theory, Strong - quantum chromodynamics). Our understanding of force involves the exchange of force carrying bosons between particles ISP209s7 Exam2 Review-3- The particles of nature T. Kondo Charge +2/3-1/3 anti-particles have opposite charge-1 ISP209s7 Exam2 Review-4- How nature is put together from the pieces Atoms Atomic Nucleus A proton (uud) Made of nuclei and electrons. Size: 10-9 m Made of neutrons and proton. Size 10-14 m Made of quarks: Size 10-15 m A neutron has ddu ISP209s7 Exam2 Review-5- A summary of the forces of nature anything with mass quarks, electrons (leptons) , neutrinos anything with charge quarks Acts on infinite Graviton (?) 6x10-39 Gravity 10-18 Only 0.001 width of proton Vector Bosons W +, W- , Z 10-6 Weak infinite photon 1/137 Electromagnetic 10-15 size of a proton Gluon, g 1 Strong Range (m) Carrier Strength Force ISP209s7 Exam2 Review-6- Our Picture of Force A charge creates a field 4 h t E Virtual particles can exist for a short time. Feynman diagram Picture of the field ISP209s7 Exam2 Review-7- Why is the sky blue? The process is more likely if the photon energy is higher. Hence blue light scatters more than red light. ISP209s7 Exam2 Review-8- Coulombs Law Charge comes in units of 1.6E-19C. How many electrons make up a charge of 2.0 C? The force between two charges is: Example (inverse square law): 4 times the distance 2 2 9 2 12 2 1 10 99 . 8 ; C Nm k r q kq F = = 1 2 r 12 ( ) d d F r q kq r q kq r q kq F 16 1 16 1 4 1 4 2 12 2 1 2 12 2 1 2 2 12 2 1 4 = = = = 19 19 10 25 . 1 10 6 . 1 . 2 ctron charge/ele charge = = = C number ISP209s7 Exam2 Review...
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This note was uploaded on 03/19/2008 for the course ISP 209 taught by Professor Sherrill during the Fall '07 term at Michigan State University.
- Fall '07