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Copy of Guglielmo Marconi and Radio Waves
Transcript of Copy of Guglielmo Marconi and Radio Waves
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December 12, 1901
A successful attempt.
Wireless signals proved effective in communication for rescue work when a sea disaster occurred.
This life-saving possibility was first realized in 1899 when a wireless message was received from the East Goodwin lightship - which had been equipped with Marconi wireless apparatus. It had been rammed in dense fog by a steamship R.F. Matthews. A request was made for the assistance of a lifeboat.
In January 1909, over 1,700 people were rescued at sea when the S.S. Republic was in collision with an Italian steamer in fog off the US East Coast. For two days in freezing conditions, Jack Binns, the Marconi radio operator on the Republic, sent messages out to help guide rescue ships to his vessel.
Other users of Marconi's radio included the Japanese Navy scouting the Russian Navy during the Russo-Japanese war in 1905 and on board the Titanic in 1912 to communicate with rescue ships in the North Atlantic.
Marconi's Waves at Sea
Light Waves and the Electromagnetic Spectrum
A Quick Glimpse of Marconi
An Italian scientist and inventor
His radio was the first to demonstrate workable wireless radio communication
Sent the first radio signals across the Atlantic
In 1909, he won the noble prize for physics
April 25, 1874
Guglielmo Marconi is born
Formed the Wireless Telegraph & Signal Company Limited (now: Marconi’s Wireless Telegraph Company Ltd.).
At a demonstration to the Italian Government at Spezia, wireless signals were sent over a distance of 12 miles!
Granted the world’s first patent for a system of wireless telegraphy.
Italian government officials were not interested in funding his work so he took his apparatus to England where Sir William Peece, Chief Engineer of the Post Office, willingly provided funds.
Began experimenting at his house in Pontecchio where he sent and received his first radio signal.
Succeeds in sending wireless signals over a distance of 1.5 miles.
As a boy, Marconi was very interested in physical and electrical science and studied the works of Maxwell, Hertz, Righi, Lodge and others.
Established the first wireless signal between France and England across the English Channel.
Founded permanent wireless stations at The Needles, Isle of Wight, at Bournemouth and later at the Haven Hotel, Poole, Dorset.
Patented a "timed spark" system for generating continuous waves.
Took out his famous patent No. 7777 for "tuned or syntonic telegraphy"
On December 12, he proved that wireless waves were not affected by the curvature of the Earth when he used his system for transmitting the first wireless signals across the Atlantic between Poldhu, Cornwall, and St. John's, Newfoundland, a distance of 2100 miles.
Demonstrated "daylight effect" relative to wireless communication and patented his magnetic detector which then became the standard wireless receiver for many years.
Transmitted the first complete messages to Poldhu from stations at Glace Bay, Nova Scotia.
Transmitted messages from Glace Bay to Cape Cod, Massachusetts.
The first transatlantic commercial service between Glace Bay and Clifden, Ireland, opened after the first shorter-distance public service of wireless telegraphy had been established between Bari in Italy and Avidari in Montenegro.
Patented his horizontal directional aerial.
Following in Marconi's footsteps...
Discovered and first produced radio waves in 1888 by applying Maxwell's theories.
He used two rods for a receiver and a spark gap as the receiving antenna. At the location where waves were picked up, a spark would jump. Hertz showed that these signals possessed all of the properties of electromagnetic waves.
What had they discovered?
You might be wondering how AM radio works. If so, AM stands for "amplitude modulation" so instead of the wave being different frequencies (widths) (like at 1:03 in the video), it would be different amplitudes (heights).
How an FM radio works:
What are radio waves used for?
FM stands for Frequency Modulation-->FM signals use various frequency levels that reproduce the sound of the originating source, for instance, music or a voice.
Watch the demo on the right to understand how a radio works.
If you would like to further understand how radio waves function in FM and AM radios watch this video. Here, you can see the various parts of the radio and possibly understand more easily how it works.
If not, continue to the next segment.
Won the Noble Prize for physics.
Developed a scientific theory to explain electromagnetic waves and first predicted radio waves through mathematical work.
He found that electrical fields and magnetic fields can group together to form electromagnetic waves. Neither an electrical field [like the static which forms when you rub your feet on a carpet], nor a magnetic field [like the one that holds a magnet onto your refrigerator] will go anywhere by themselves.
James Clerk Maxwell
Discovered that using smaller spheres on the exciters caused the production of shorter electromagnetic waves
Made mechanical improvements to Hertz's oscillator design, leading to more control over and consistency in the waves produced, and confirmed Maxwell's electromagnetic theory of light
Made discoveries in the field of wireless transmission
Demonstrated the importance of inductive effects in the transmission of signals along long telegraph lines and undersea telegraph cables
1. demonstrated that the velocity of radio waves was equal to the velocity of light, and with that, that radio waves were a form of light.
2. found out how to make the electric and magnetic fields detach themselves from wires and go free as Maxwell's waves.
The unit of frequency of a radio wave -- one cycle per second -- is called the hertz, in his honor.
Marconi wrote about the experience...
"Shortly before midday I placed the single earphone to my ear and started listening. The receiver on the table before me was very crude -- a few coils and condensers and a coherer -- no valves, no amplifiers, not even a crystal. But I was at last on the point of putting the correctness of all my beliefs to test. The answer came at 12: 30 when I heard, faintly but distinctly, pip-pip-pip. I handed the phone to Kemp: "Can you hear anything?" I asked. "Yes," he said. "The letter S." He could hear it. I knew then that all my anticipations had been justified. The electric waves sent out into space from Poldhu had traversed the Atlantic -- the distance, enormous as it seemed then, of 1,700 miles -- unimpeded by the curvature of the earth. The result meant much more to me than the mere successful realization of an experiment. As Sir Oliver Lodge has stated, it was an epoch in history. I now felt for the first time absolutely certain that the day would come when mankind would be able to send messages without wires not only across the Atlantic but between the farthermost ends of the earth."
Marconi attempted to send the first radio signals across the Atlantic Ocean, in spite of predictions that the radio waves would be lost as the earth curved over that long distance.
He set up a specially designed wireless receiver in Newfoundland, Canada, using a coherer (a glass tube filled with iron filings) to conduct radio waves, and balloons to lift the antenna as high as possible. The signals were sent in Morse code from Poldhu, Cornwall, in England.
Greatly improved the performance of Hertz's apparatus. The distance for transmission and reception of signals progressively augmented: "across a room, down the length of a corridor, from the house and then into fields"
Made advances in the wireless telephony of public broadcasting
Developed a successful system of radio telegraphy
Developed the basis of nearly all modern radio broadcasting through his work on the development of shortwave wireless communication
Extended the range of radio signaling using his aerials
Established communication across the English Channel
Established the American Marconi Co
Sent the first signals across the Atlantic
Although we may not see radios like these on a daily basis--except for in my house--we use FM radios everyday...the perfect example that demonstrates the function and properties of radio waves is an FM radio.
Radio waves have the longest wavelengths in the electromagnetic spectrum and vary from 1 mm to 100 km.
They are generally used by antennas and are used for the transmission of data.
Now...what exactly are radio waves and what do we use them for?
On 15th June, the first advertised public broadcast programme in Britain took place. A song by Dame Nellie Melba was broadcast using a Marconi 15 kW telephone transmitter and was heard in many countries.
BBC adopted the Marconi-EMI system for its public high definition television service--the first one in the world.
Built the first microwave telephone system and helped open the way for a revolution in microwave electronic communication.
Received the John Fritz medal, the most prestigious in American Engineering.
By this time, Marconi had developed shortwave directional transmission, named The Bean System.
This was a new development far superior to the longwave high power system in several ways:
short-wave stations did not require large, powerful transmission systems and cost less to build and use.
short waves, unlike long waves, could be used as effectively during the day as at night.
*the beam system made short-wave radio an efficient and reliable method of communication.
July 20, 1937
Guglielmo Marconi dies
Radio-telegraphy is the sending of the same dot-dash message (morse code) used in a telegraph by radio wave. Transmitters were called spark-gap machines.
Carry signals for televisions:
The antenna visible on "old" television sets receives the signal, in the form of electromagnetic waves, that is broadcasted from the television station. It is displayed on your television screen.
Cable companies have antennae or dishes which receive waves broadcasted from your local TV stations. The signal is then sent through a cable to your house.
Bring music to radios.
Carry time signals to watches that can calibrate themselves.
Carrys information through countless other forms of wireless communication, for example, wireless internet, headphones, controllers, etc.
Carry signals for cell phones:
Radio waves used to transmit information via cell phones are much smaller that TV and FM radio waves.
If you want to learn more about Guglielmo Marconi visit this link and explore the website for more information on radio waves and its various applications:
In wireless telegraphy, the conducting medium is not wire as in landline telegraphy, but air.
The transmitting antenna radiates the radio waves created by the originating current from the spark coils—at the speed of light in every direction. This signal is then available to any receiving antenna within its range.
A receiving antenna will reverse this process, converting the airborne radio waves it detects to an electric current which is translated at the receiving station.
c = the speed of light, which is about 3 x 10^8 m/s
h = Planck's constant, which is about 6.63 x 10-27 erg/s, where an erg is a unit of energy.
Essentially, since the energy of an electromagnetic wave is directly proportional to its frequency and inversely proportional to its wavelength, the higher the energy of the wave, the higher the frequency, and the shorter the wavelength.
Light consists of electromagnetic (EM) waves.
electromagnetic wave: composed of an electric field and a magnetic field that oscillate together. These fields are perpendicular to each other, and the wave travels in a direction perpendicular to both of the fields.
In other words, these electromagnetic waves are transversal.
Electromagetic waves have some important properties:
wavelength: the distance between two adjacent crests of the wave [units: lengths such as meter]
frequency (f): the number of wave oscillations per second [units: Hertz]
(1 Hz = 1 wave crest per second)
energy (E) of the individual photons in the wave.
For all types of electromagnetic radiation, the relationships between wavelength, frequency, and energy are:
These waves can are also particles called photons.
photons: massless packets of energy that travel at the speed of light.
Electromagnetic radiation behaves both as a particle and a wave.
The types of electromagnetic radiation are gamma, X-ray, Ultraviolet, visible light, infrared, microwave, and radio waves.
Radio waves can carry information by varying a combination of the amplitude, frequency, and phase of the wave within a frequency band.
When a radio wave reaches a conductor, it transfers to the conductor, travels along it, and induces an electric current on the surface of that conductor by exciting the electrons of the conducting material. This effect, known as the skin effect, is used in antennas.
You might have noticed that FM radio has mostly music while AM radio mostly includes news and talk programs. This is because frequency modulation allows the transmission of the greater range of frequencies music contains.