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Physics 102: Journey through Electricity, Magnetism & more

Explore the world of Physics 102 covering Electricity, Magnetism, Optics, Atomic Physics, Nuclear Physics, and Relativity with engaging lectures and interactive activities. Dive into the basics of charge, conductors, and insulators. Enhance your understanding of Coulomb's Law and forces between charges.

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Physics 102: Journey through Electricity, Magnetism & more

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  1. Welcome to Physics 102! • Electricity + Magnetism • Optics • Atomic Physics • Nuclear Physics • Relativity http://online.physics.uiuc.edu/courses/phys102/ Physics 102: Lecture 1, Slide 1

  2. Meet the Lecturer • George Gollin g-gollin@uiuc.edu • Research • Elementary Particle Experimental Physics http://online.physics.uiuc.edu/courses/phys102/ Physics 102: Lecture 1, Slide 2

  3. Course Format(Spiral Learning) • Preflights 50 • Homework 100 • Lab 150 • Discussion 150 • Take-home quizzes; drop lowest 1 • Hour Exams (3 x 100) 300 • Final Exam 250 1000 Physics 102: Lecture 1, Slide 3

  4. 950-1000 A+ 920-949 A 900-919 A- 880-899 B+ 860-879 B 835-859 B- 810-834 C+ 780-809 C 750-779 C- 720-749 D+ 690-719 D 610-689 D- <610 F Grading Scale Physics 102: Lecture 1, Slide 4

  5. Reading & Lecture • Do it! • Answer preflights 50/1000 points • 2 points for honest attempt at preflight. • Must do the entire preflight to earn any credit Physics 102: Lecture 1, Slide 5

  6. P102 Lectures • Not everything you need! • Concepts, Connections, Motivation • ComprehensiveTextbook • Calculations Homework + Discussion • Hands-OnLab • Taking Notes • Lecture notes will be available at bookstore or online • Some key pieces for you to fill in Physics 102: Lecture 1, Slide 6

  7. Origin of Charge • Charge is an intrinsic property of matter • Two types: • Positive Charge: Protons • Negative Charge: electrons • Opposites Attract! (likes repel) • Atoms are neutral • Negatively charged electrons “orbit” r~10-10 m • Positively charged central nucleus r~10-15 m Physics 102: Lecture 1, Slide 7

  8. Q: How do electrons behave in a perfect conductor? Q: How do electrons behave in a perfect insulator? Conductors and Insulators A: A: Most things are in between perfect conductor / insulator Physics 102: Lecture 1, Slide 8

  9. Electroscope • Conduction • Charged rod is brought near scope • Charged rod touches scope transferring some charge • Scope is left w/ same charge as rod • Induction • Charged rod is brought near scope • Scope is briefly grounded allowing charge to flow on (or off) scope • Scope is left w/ opposite charge as rod Physics 102: Lecture 1, Slide 9

  10. ACTS • A negatively charged rod is used to charge an electroscope by induction. What is the resulting net charge on the electroscope? 1) positive 2) zero 3) negative • If the conducting electroscope were replaced by an insulating ball and then charged by induction as above, what would be the net charge on the ball. 1) positive 2) zero 3) negative Physics 102: Lecture 1, Slide 10

  11. ACTS • A negatively charged rod is used to charge an electroscope by induction. What is the resulting net charge on the electroscope? 1) positive 2) zero 3) negative • If the conducting electroscope were replaced by an insulating ball and then charged by induction as above, what would be the net charge on the ball. 1) positive 2) zero 3) negative Physics 102: Lecture 1, Slide 11

  12. Qp=1.6x10-19 C Qe = -1.6x10-19 C + - r = 1x10-10 m Example Coulomb’s Law • Magnitude of the force between charges q1 and q2 separated a distance r: • F = k q1q2/r2 k = 9x109 Nm2/C2 • Force on electron in Hydrogen atom Physics 102: Lecture 1, Slide 12

  13. qp=1.6x10-19 C qe = -1.6x10-19 C + - r = 1x10-10 m F ACT: Coulomb’s Law • What is the direction of the force on the proton due to the electron? (1) Left (2) Right (3) Zero • What is the magnitude of the force on the proton due to the electron? Example F= _______ N Physics 102: Lecture 1, Slide 13

  14. qp=1.6x10-19 C qe = -1.6x10-19 C + - r = 1x10-10 m F ACT: Coulomb’s Law • What is the direction of the force on the proton due to the electron? (1) Left (2) Right (3) Zero • What is the magnitude of the force on the proton due to the electron? Example F= 2.3x10-8 N Physics 102: Lecture 1, Slide 14

  15. ACT A positive and negative charge with equal magnitude are connected by a rigid rod, and placed near a large negative charge. What is the net force on the two connected charges? 1) Left 2) Zero 3) Right - + - Physics 102: Lecture 1, Slide 15

  16. ACT A positive and negative charge with equal magnitude are connected by a rigid rod, and placed near a large negative charge. What is the net force on the two connected charges? 1) Left 2) Zero 3) Right Positive charge is attracted (force to left) Negative charge is repelled (force to right) Positive charge is closer so force to left is larger. - + - Physics 102: Lecture 1, Slide 16

  17. ACT: Induced Dipole • An uncharged conducting sphere is hung next to a charged sphere. What happens when the uncharged sphere is released? 1) Nothing 2) Attracted to charged sphere. 3) Repelled from charged sphere. Physics 102: Lecture 1, Slide 17

  18. ACT: Induced Dipole • An uncharged conducting sphere is hung next to a charged sphere. What happens when the uncharged sphere is released? 1) Nothing 2) Attracted to charged sphere. 3) Repelled from charged sphere. Physics 102: Lecture 1, Slide 18

  19. ACT: Induced Dipole • An uncharged conducting sphere is hung next to a charged sphere. What happens when the uncharged sphere is released? 1) Negative charge attracts + repels - Physics 102: Lecture 1, Slide 19

  20. ACT: Induced Dipole • An uncharged conducting sphere is hung next to a charged sphere. What happens when the uncharged sphere is released? 1) Negative charge attracts + repels - 2) Since + is closer, attractive force is strongest Physics 102: Lecture 1, Slide 20

  21. ACT: Induced Dipole • An uncharged conducting sphere is hung between a charged sphere and a grounded sphere and held midway between the two. What happens when the uncharged sphere is released? • An uncharged conducting sphere is hung between a charged sphere and a grounded sphere and held midway between the two. What happens when the uncharged sphere is released? 1) Negative charge attracts + repels – 2) Since + is closer, attractive force is strongest Physics 102: Lecture 1, Slide 21

  22. To Do • Read Sections 16.1-6 • Do your preflight before 8:00 AM on the day of lecture. See you next time! Physics 102: Lecture 1, Slide 22

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