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UNIVERSITY OF NEBRASKA-LINCOLN

UNIVERSITY OF NEBRASKA-LINCOLN

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UNIVERSITY OF NEBRASKA-LINCOLN

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  1. 6348 Fill in this call number for our section: 0 0 0 0 1 1 1 1 2 2 2 2 3 3 3 3 4 4 4 4 5 5 5 5 6 6 6 6 7 7 7 7 8 8 8 8 9 9 9 9 UNIVERSITY OF NEBRASKA-LINCOLN No. No. 6348 0 0 0 0

  2. average Class Averages (3 exams w/bonus points and homework quizzes) 70.4 35 40 45 50 55 60 65 70 75 80 85 90 95 100 + 95 90 - 85 + 80 75 - 70 + 65 60 - 55 + 50 45 - 40 A These cutoffs will not be raised…you can use them to determine your guaranteed lowest grade. B C D

  3. The switch is closed on this simple circuit of an electromagnet: + - What might affect how rapidly current reaches its maximum value? I = V/R time switch is closed time

  4. Leyden, Holland (1746) Petrus van Musschenbroek

  5. The Leyden Jar capacitor + + + + + + + - - - - - - -

  6. Discharging through an inductor should slow the process down: The act of discharging through an inductor creates a short-lived electromagnet. But rather than vanishing immediately the strength of the electromagnet fades slowly as an induced voltage tries to sustain the current a little longer! Remember the inductor slows down both turn-on and the turn-off.

  7. + + + + – – – – Fully charged capacitor I I + + – – Current starts to flow I Maximum positive current I Maximum current I

  8. I I + + – – + + + + – – – – + + – – Current begins to die down I Capacitor fully charged I I Current flows (oppositedirection!)

  9. Oscillators I I + + + + – – – – + + – – Current starts to flow Energy:someE, some B Fully charged capacitor Energy: all E • Current begins to die down • induced   • C charges in opposite direction • Energy: someE, someB Maximum current Energy:all B I + + – – Current flows (oppositedirection!) Energy:someE, some B Capacitor charged Energy:allE I + + + + – – – – + + – –

  10. Transmitting antenna “Oscillator” The “tank circuit” the text talks about

  11. Receiving antenna “variable capacitor” to speakers tunable oscillator

  12. induction coil variable capacitor

  13. 1 Frequency size of capacitor size of inductor A small surface area capacitor A single loop: A specially shaped metal “C”: tiny capacitor ++++ ---- small inductance coil 2.45 GHz

  14. A microwave’s MAGNETRON - - - - ++++ - - - - ++++ - - - - ++++ - - - - ++++

  15. E c B Recall: the water molecule is slightly “polar” - + + + - it has “sides” that are oppositely charged +

  16. tungsten heating filament - - - - - -- + accelerated electrons slam into the “anode” + + + + + + + +

  17. In which direction are the generated x-rays most likely to be traveling? - - - - - -- + A + + + + B + + + + C

  18. 6348 Fill in this call number for our section: 0 0 0 0 1 1 1 1 2 2 2 2 3 3 3 3 4 4 4 4 5 5 5 5 6 6 6 6 7 7 7 7 8 8 8 8 9 9 9 9 UNIVERSITY OF NEBRASKA-LINCOLN No. No. 6348 0 0 0 0