Direct Current Circuit

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• Direct Current Circuit
• A bimetallic strip flasher
• ????????bimetallic strip,???????,????????

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Ex.3-1 Bimetallic Strip Flasher
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Ex. 3-2 ??????????(??)??
???? Kirchhoff ????
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Ex.3-3 The Ammeter and the Voltmeter
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Ex. 3-4 RC??

• ??-????

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Ex. 3-4 (cont)

• ?? R 10M? C 1?F
• ??46s?,e 0.01,???99?
• ??????????????

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• Alternating Current Circuit
• V( t ) V0Sin2?f t
• f ?? 60H(?)
• V0 ???,
• ?????170V

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• P(t) I0V0Sin2 2? f t,??????
• ??????,??????

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Ex.3-5 A practical example Quebec ?Montreal
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Ex. 3-5 72W ??
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Automatic Coffee Maker
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3-way Light Bulb
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Electrical Grounding
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III.2 ??(Magnetism)

• ??????
• ??
• ??
• ??
• ????????
• ????
• ????????
• ?????

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• ????,???? ? ???????? or ??????? ? ???
• ???

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??
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• ?????????,??????????????11.5º
• ???????????(0.01?of C )??,??????(bow shock)

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?????

• How can a clay-walled kiln reveal Earths
• magnetic field of the past?

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The SI unit for B
1 tesla 1T 1 N/A?m104 gauss
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• The frequency and angular frequency
• Helical Paths

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• The pitch (??) of the helical path

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Earth as a dipole field
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Van Allen Belt
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Magnetic Mirror
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Charged Particles from the Sun
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Auroras the Northernand Southern Lights
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UV and X-ray emissions from Aurora
UV emission from northern aurora observed by the
Polar satellite
X-ray emission from northern aurora observed by
the Polar Satellite
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The Mass Spectrometer
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Isotope Separation Centrifuge and diffusion
chamber
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????? (cyclotrons)

• ?????????????,?????????????)

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????? (synchrotrons)

• The resonance condition
• When proton energy gt 50Mev
• Out of resonance (relativistic effect)
• A huge magnet (4106 m2) is needed for high
  energy (500Gev) protons
• The proton sychrotron at Fermilab can produces
  1Tev proton

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Fermilab 6.3km Tevatron
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Speaker
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Voice-coil positioner of a HDD
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MHD Propulsion
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Maglev Trains
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EM Rail Gun
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Magnetic Resonance Imaging
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III.3 ????

• Two symmetric Situations
• current loop magnetic field ? torque
• torque magnetic field ? current
• Two Experiments
• Applications

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First Experiment

• A Magnet is moving with respect to the loop

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Second Experiment
The switch S is closed or opened
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Faradays law

• An emf is induced when the number of magnetic
  field lines that pass through the loop is changing

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A Simple Example
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Magnetic Tape Recording
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Electric Guitar
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The Playback Head
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The moving-coil microphone
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Transformer
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Transmitting Electricity
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Eddy currents
The electromagnetic braking
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Metal detector
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III.4 ???

• ???????????
• ????????????????????
• ?????(??)
• ??(Laser)