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Chemist, physicist
Attended lectures by Humphrey Davy, who later took him on as secretary/scientific assistant
Faraday found that the electromotive force (EMF) produced around a closed path is proportional to the rate of change of the magnetic flux through any surface bounded by that path.
Fardays Law
ewhere e= electromagnetic force (volts)
eand FB=  magnetic flux (webers)
eN number of turns of wire
e
b 1831, Edinburgh
1885-1886 also developed Kinetic theory of gases, groundwork for thermodynamics.
1859 showed saturn’s rings must be composed of many small particles
1861 First colour photograph
Maxwell’s disk in photo
Linked set of differential equations
20 DEs in 20 variables
Simpler expressed in vector notation (as above)
s· Divergence Operator
s× Curl Operator
H Magnetic field
E Electric field
J Free Current Density
rElectric Charge Density
re Electrical permittivity of material
rm Magnetic permeability of material
Linked set of differential equations
20 DEs in 20 variables
Simpler expressed in vector notation (as above)
s· Divergence Operator
s× Curl Operator
H Magnetic field
E Electric field
J Free Current Density
rElectric Charge Density
re Electrical permittivity of material
rm Magnetic permeability of material
This velocity is so nearly that of light, that it seems we have strong reason to conclude that light itself (including radiant heat, and other radiations if any) is an electromagnetic disturbance in the form of waves propagated through the electromagnetic field according to electromagnetic laws.
Now know that light, radio waves, xrays, gamma etc are all forms of electromagnetic radiation
Primary circuit
cf. Electric Bell
Why Capacitor?
Coil tries to keep current flowing (self-inductance) č large voltage will develop across interrupter on break č arcing č contacts wear.
Capacitor acts to prevent voltage building up too rapidly on contacts.
Also, capacitor & coil form resonant circuit, energy passes between them & circuit ‘rings’ at resonant frequency
Experiment needed to be done in dark & use magnifying glass to observe sparks at receiver.
Hertz did experiments with setup & established:
E/M waves can travel distance, as postulated by Faraday & Maxwell
Didn’t appreciate significance
It's of no use whatsoever[...] this is just an experiment that proves Maestro Maxwell was right - we just have these mysterious electromagnetic waves that we cannot see with the naked eye. But they are there."
Also determined that some material transmit radio waves and some materials reflect them.
discovered standing waves
"wireless transmission of data using the entire frequency spectrum”
The coherer was the first widely used detector for radio communication.
Branly built upon the discoveries of Temistocle Calzecchi-Onesti, who demonstrated in experiments in 1884 through 1886 that iron filings contained in an insulating tube will conduct an electrical current under the action of an electromagnetic wave.
The operation of the coherer is based upon the large resistance offered to the passage of electric current by loose metal filings, which decreases under the influence of radio frequency alternating current.
The coherer became the basis for radio reception, and remained in widespread use for about ten years.
b, 1856, Croatia.
d, 1943, New York
According to legend, Tesla was born precisely at midnight during an electrical storm, to a Serb family located in present-day Croatia
In addition to radio work also worked on
Various electric motors
AC power transmission (eg 3 phase supply)
ARC lights
x-ray tubes – noted that x-rays burned his skin !!
flourescent lights
Born Bolgna, Italy
Repeated spark gap, coherer experiments of other people. Experimented with different antennae configurations,
Photo of marconi in 1903 – note induction coil & spark gap, also paper tape output of morse code.
Didn’t make any money out of radio until loss of Titanic in 1912.
Message from SS Olympic, 14th April 1912
“SS Titanic ran into iceberg. Sinking fast.”
Braun shared 1909 Nobel prize with Marconi