1. Lecture 19-1 Potential Difference Across Inductor VV ++ - I internal resistance Analogous to a battery An ideal inductor has r=0 All dissipative effects are to be included in the internal resistance (i.e., those of the iron core if any)

2. Lecture 19-2 Ways to Change Magnetic Flux Changing the magnitude of the field within a conducting loop (or coil). Changing the area of the loop (or coil) that lies within the magnetic field. Changing the relative orientation of the field and the loop. motor generator http://www.wvic.com/how-gen-works.htm

3. Lecture 19-3 Alternating Current (AC) = Electric current that changes direction periodically ac generator is a device which creates an ac emf/current. ac motor = ac generator run in reverse A sinusoidally oscillating EMF is induced in a loop of wire that rotates in a uniform magnetic field. where http://www.wvic.com/how-gen-works.htm http://www.pbs.org/wgbh/amex/edison/sfeature/acdc.html

4. Lecture 19-4 Resistive Load Start by considering simple circuits with one element (R, C, or L) in addition to the driving emf. Pick a resistor R first. v R (t) and I(t) in phase Kirchhoff’s Loop Rule: I peak + -- I(t)

5. Lecture 19-5 City lights viewed in a motion blurred exposure. The AC blinking causes the lines to be dotted rather than continuous (quote from Wikipedia)

6. Lecture 19-6 Power Dissipated by Resistive Load V R and I in phase Power:

7. Lecture 19-7 Average Power but

8. Lecture 19-8 Root-Mean-Square Values Similarly,

9. Lecture 19-9 Non-scored Test Quiz Which of the following statement is true? A. B. C. D.

10. Lecture 19-10 Capacitive Load I(t) leads v(t) by 90  (1/4 cycle) Loop Rule: Power: +--

11. Lecture 19-11 Inductive Load v L (t) leads I(t) by 90  (1/4 cycle) Kirchhoff’s Loop Rule: Power: +--

12. Lecture 19-12 -- Capacitive vs Inductive Load I(t) leads v(t) by 90  capacitive reactance + -- + v L (t) leads I(t) by 90  inductive reactance vLvL

13. Lecture 19-13 (Ideal) LC Circuit From Kirchhoff’s Loop Rule From Energy Conservation same Natural Frequency harmonic oscillator with angular frequency

14. Lecture 19-14 LC Oscillations No Resistance = No dissipation

15. Lecture 19-15 Physics 241 –Quiz 16b – March 20, 2008 In most of Europe, the peak voltage of household outlets is 311 V. What is the rms voltage? a)110 V b)141 V c)156 V d)220 V e)311 V

16. Lecture 19-16 Physics 241 –Quiz 16c – March 20, 2008 In Japan, the rms voltage of household outlets is 100V. What is the peak voltage? a)200 V b)141 V c)100 V d)50 V e)71 V