AC Power, Current Wars, The Thing, The Thereminasmith/Physics2220... · employees, of Topsy, a...
Transcript of AC Power, Current Wars, The Thing, The Thereminasmith/Physics2220... · employees, of Topsy, a...
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Lecture 25AC Power, Current Wars,The Thing, The Theremin
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Damped Oscillations: RLC circuits
Energy gradually dumped into
resistor: i^2*R
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Alternating Current
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Alternating Current
For Example: in USA, V=120 V AC, 60 Hz
But Why Bother?
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2 reasons: Transformers and Power loss:
P=i^2RMaintain low current and high voltage for
transmission
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Current Wars
vs
Edison Westinghouse/Tesla
DC AC
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Edison's publicity campaign (from Wikipedia)
Edison carried out a campaign to discourage the use of alternating current, including spreading disinformation on fatal AC accidents, publicly killing animals, and lobbying against the use of AC in state
legislatures. Edison directed his technicians, primarily Arthur Kennelly and Harold P. Brown, to preside over several AC-driven executions of animals, primarily stray cats and dogs but also unwanted cattle
and horses. Acting on these directives, they were to demonstrate to the press that alternating current was more dangerous than Edison's system of direct current. He also tried to popularize the term for being electrocuted as being "Westinghoused". Years after DC had lost the "war of the currents," in 1902, his film crew made a movie of the electrocution with high voltage AC, supervised by Edison
employees, of Topsy, a Coney Island circus elephant who had recently killed a man.
Edison opposed capital punishment, but his desire to disparage the system of alternating current led to the invention of the electric chair. Harold P. Brown, who was at this time being secretly paid by Edison,
constructed the first electric chair for the state of New York in order to promote the idea that alternating current was deadlier than DC.
When the chair was first used, on August 6, 1890, the technicians on hand misjudged the voltage needed to kill the condemned prisoner, William Kemmler. The first jolt of electricity was not enough to kill Kemmler, and only left him badly injured. The procedure had to be repeated and a reporter on hand
described it as "an awful spectacle, far worse than hanging." George Westinghouse commented: "They would have done better using an axe."
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Tesla on the other hand....
“We are like tenant farmers chopping down the fence around our house for fuel when we should be using
Natures inexhaustible sources of energy — sun, wind and tide. ..
Radio, AC Power, florescence, ignition
systems......
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Tesla on the other hand....
“There is no thing endowed with life—from man, who is enslaving the elements, to the nimblest creature—in all this world that does not sway in its turn. Whenever action is born from force, though it be infinitesimal, the cosmic balance is upset and the universal motion results.”
Radio, AC Power, florescence, ignition
systems......
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Phasor Notation:
• http://www.animations.physics.unsw.edu.au/jw/AC.html
• http://science.sbcc.edu/physics/flash/optics/phasors4.swf
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http://www.animations.physics.unsw.edu.au/jw/AC.htmlhttp://www.animations.physics.unsw.edu.au/jw/AC.htmlhttp://www.animations.physics.unsw.edu.au/jw/AC.htmlhttp://www.animations.physics.unsw.edu.au/jw/AC.htmlhttp://science.sbcc.edu/physics/flash/optics/phasors4.swfhttp://science.sbcc.edu/physics/flash/optics/phasors4.swfhttp://science.sbcc.edu/physics/flash/optics/phasors4.swfhttp://science.sbcc.edu/physics/flash/optics/phasors4.swf
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Diode
Current is allowed in one direction, but not the other
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Use Diodes to build “rectifiers”
Half wave:
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Full Wave:
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DC is then smoothed with “filters”
High pass filter
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DC is then smoothed with “filters”
Low pass filter
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Leon Theremin (1896-1993)
• Theremin – the classic Theremin (1920)• Burglar alarm, or "Signalling Apparatus" which
used the Theremin effect (1920s)• Electromechanical television – Nipkow disk
with mirrors instead of slots (ca. 1925)• Terpsitone – platform that converts dance
movements into tones (1932)• Theremin cello – an electronic cello with no
strings and no bow, using a plastic fingerboard, a handle for volume and two knobs for sound shaping (ca. 1930)[32][33][34][35]
• Keyboard theremin (ca. 1930), looking like a small piano, "with hornlike tones"[36]
• Rhythmicon – world's first drum machine (1931)
• The Buran eavesdropping device (1947 or earlier)
• The Great Seal bug, also known as "The Thing" – one of the first passive covert listening devices; first used by the USSR for spying (1945 or earlier)
Soviet Inventor/ KGB Espionage Engineer
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http://en.wikipedia.org/wiki/Burglar_alarmhttp://en.wikipedia.org/wiki/Burglar_alarmhttp://en.wikipedia.org/wiki/Mechanical_televisionhttp://en.wikipedia.org/wiki/Mechanical_televisionhttp://en.wikipedia.org/wiki/Nipkow_diskhttp://en.wikipedia.org/wiki/Nipkow_diskhttp://en.wikipedia.org/wiki/Terpsitonehttp://en.wikipedia.org/wiki/Terpsitonehttp://en.wikipedia.org/wiki/Cellohttp://en.wikipedia.org/wiki/Cellohttp://en.wikipedia.org/wiki/L%C3%A9on_Theremin#cite_note-32http://en.wikipedia.org/wiki/L%C3%A9on_Theremin#cite_note-32http://en.wikipedia.org/wiki/L%C3%A9on_Theremin#cite_note-33http://en.wikipedia.org/wiki/L%C3%A9on_Theremin#cite_note-33http://en.wikipedia.org/wiki/L%C3%A9on_Theremin#cite_note-34http://en.wikipedia.org/wiki/L%C3%A9on_Theremin#cite_note-34http://en.wikipedia.org/wiki/L%C3%A9on_Theremin#cite_note-35http://en.wikipedia.org/wiki/L%C3%A9on_Theremin#cite_note-35http://en.wikipedia.org/wiki/L%C3%A9on_Theremin#cite_note-36http://en.wikipedia.org/wiki/L%C3%A9on_Theremin#cite_note-36http://en.wikipedia.org/wiki/Rhythmiconhttp://en.wikipedia.org/wiki/Rhythmiconhttp://en.wikipedia.org/wiki/Drum_machinehttp://en.wikipedia.org/wiki/Drum_machine
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“The Thing” or “Great Seal Bug”
Theremins device was implanted inside a carved
wooden plaque of the US seal given to ambassador to Soviets as a gesture of friendship. Was
discovered by British radio operator and reverse
engineered by MI5. Later was presented at special UN
meeting in response to the downing of the U2 spy plane
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Forced Oscillations in 3 Easy Pieces
• Resistive Load• Capacitive Load• Inductive Load
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•Phase angle (ϕ) = 0•Current and Voltage are in phase
Alternating CurrentPurely Resistive Load:
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•Phase angle (ϕ) =-90•Voltage “lags” current
Alternating CurrentPurely Capacitive Load:
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•Phase angle (ϕ) =+90•Voltage “leads” current
Alternating CurrentPurely Inductive Load:
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Type Resistance Phase of (i) V relation
R
C
L
R
X = 1/ωC
LX = ωL
C
0
leads v by 90
lags v by 90
0
0
V=IR
V=IX
V=IX
C
L
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Leon Theremin (1896-1993)
• Theremin – the classic Theremin (1920)• Burglar alarm, or "Signalling Apparatus" which
used the Theremin effect (1920s)• Electromechanical television – Nipkow disk
with mirrors instead of slots (ca. 1925)• Terpsitone – platform that converts dance
movements into tones (1932)• Theremin cello – an electronic cello with no
strings and no bow, using a plastic fingerboard, a handle for volume and two knobs for sound shaping (ca. 1930)[32][33][34][35]
• Keyboard theremin (ca. 1930), looking like a small piano, "with hornlike tones"[36]
• Rhythmicon – world's first drum machine (1931)
• The Buran eavesdropping device (1947 or earlier)
• The Great Seal bug, also known as "The Thing" – one of the first passive covert listening devices; first used by the USSR for spying (1945 or earlier)
Soviet Inventor/ KGB Espionage Engineer
Friday, November 15, 13
http://en.wikipedia.org/wiki/Burglar_alarmhttp://en.wikipedia.org/wiki/Burglar_alarmhttp://en.wikipedia.org/wiki/Mechanical_televisionhttp://en.wikipedia.org/wiki/Mechanical_televisionhttp://en.wikipedia.org/wiki/Nipkow_diskhttp://en.wikipedia.org/wiki/Nipkow_diskhttp://en.wikipedia.org/wiki/Terpsitonehttp://en.wikipedia.org/wiki/Terpsitonehttp://en.wikipedia.org/wiki/Cellohttp://en.wikipedia.org/wiki/Cellohttp://en.wikipedia.org/wiki/L%C3%A9on_Theremin#cite_note-32http://en.wikipedia.org/wiki/L%C3%A9on_Theremin#cite_note-32http://en.wikipedia.org/wiki/L%C3%A9on_Theremin#cite_note-33http://en.wikipedia.org/wiki/L%C3%A9on_Theremin#cite_note-33http://en.wikipedia.org/wiki/L%C3%A9on_Theremin#cite_note-34http://en.wikipedia.org/wiki/L%C3%A9on_Theremin#cite_note-34http://en.wikipedia.org/wiki/L%C3%A9on_Theremin#cite_note-35http://en.wikipedia.org/wiki/L%C3%A9on_Theremin#cite_note-35http://en.wikipedia.org/wiki/L%C3%A9on_Theremin#cite_note-36http://en.wikipedia.org/wiki/L%C3%A9on_Theremin#cite_note-36http://en.wikipedia.org/wiki/Rhythmiconhttp://en.wikipedia.org/wiki/Rhythmiconhttp://en.wikipedia.org/wiki/Drum_machinehttp://en.wikipedia.org/wiki/Drum_machine
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“The Thing” or “Great Seal Bug”
Theremins device was implanted inside a carved
wooden plaque of the US seal given to ambassador to Soviets as a gesture of friendship. Was
discovered by British radio operator and reverse
engineered by MI5. Later was presented as special UN
meeting in response to the downing of the U2 spy plane
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Meissner Effect
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Pulsars-Highly magnetized
remnant of supernova explosion
-B-field inclined with respect to angular
motion
As star rotates, B field sweeps radiation past our line of sight->
lighthouse effectFriday, November 15, 13
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Jocelyn Bell-Discovery:1967
Dubbed: LGM-1
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