Demos ► Phonograph Needle, turntable, microscope, vinyl record ► Regenerative Breaking with two generators. ► Microphone or Speaker and Oscilloscope ► Buzzer ► Coil inside tape player ► Electromagnet (coil) and yardstick w/ magnet ► Animal Cube Child’s Toy ► Van de Graph and radios ► Polarized Filters ► Slinky and telephone cord ► Hydrogen Fuel Cell + Solar Cell

Brief Timeline of telegraph and radio 1833: Electrical Telegraph – using electricity in wires to transmit dots and dashes. 1835: Relay is developed 1866: First transatlantic cable is successfully laid on ocean floor, to be used for the telegraph. 1876: First telephone (wires used to transmit voice, not just Morse codes) 1894: First use of wireless telegraph (transmitting Morse codes without the use of wires) 1906: First radio broadcast (transmitting voice without wires)

Samuel Morse develops a code comprised of dots and dashes. Morse develops the electromagnetic telegraph. A series of Clicks and Clacks were heard at the relay. A weak current from The sender activates a relay that connects a battery to the sounder.

Sounder – Self Interrupting Circuit Voltage Source Switch or Relay

1866 – Laying the transatlantic cable ► Five attempts to lay cable in 12 years ► 1866 cable was able to transmit eight words a minute

Alexander Graham Bell and the Telephone ► Very interested in assisting the deaf. Both his mother and wife were deaf. ► Devised hearing aides ► Taught in a school for the deaf ► Used the concept of Electromagnetic Induction to convert sound waves (pressure wave) into electrical signals in 1876 ► A sound wave is a vibration of air molecules. Wikipedia

Bell patents the electro-magnetic transmission of vocal sound by undulatory electric current in Microphone

Bell’s First Telephone- Liquid Transmitter The sound wave vibrates the diaphragm that in turn moves a rod up and down. This changes the resistance making the Electrical current change in response to the sound wave.

Another Transmitter (The Microphone)

G. Bell built multiple receivers using various technologies.

It is important to note that there is no one "inventor of the telephone". Bell was merely the first to patent the telephone. 16 years prior to this, Antonio Meucci, who did not have $10 to file a patent, demonstrated his electro-magnetic "teletrofono" in New York in Antonio Meucci Wikipedia A 2002 a resolution by the U.S. House of Representatives, gave its endorsement of Antonio Santi Giuseppe Meucci as the originator of the telephone. HR 269

This Technology became a basic component of telephones for almost a hundred years. The Carbon Transmitter (microphone)

First Telephone – The Transmitter and Receiver are the same.

Edison’s Recording Devices The Phonograph in 1877 used telephone technology to record sounds on a wax cylinder. Smithsonian The first voice recorder

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Sound waves can be stored directly in their analog form by cutting grooves on vinyl.

Record Needle - Stylus Contacts the recorded disc and transfers its vibrations to the rest of the system Contacts the recorded disc and transfers its vibrations to the rest of the system As the stylus rides along the walls of the moving groove, it vibrates back and forth. Two transducers attached to this stylus sense its motions and produce electric currents that are related to those motions. (A coil of wire and a magnet move relative to one another as the stylus moves and this causes current to flow through the coil.) Louis A. Bloomfieldhttp:// Transducer: converts input energy of one form into output energy of another.

So far we have: Using wires to transmit short and long buzzes Using wires to transmit short and long buzzes Using wires to transmit voice and music. Using wires to transmit voice and music.

Maxwell’s Equations 1. Like charges repel, unlike charges attract 2. Magnetic fields always have two poles (positive and negative) 3. A moving/changing magnetic field produces an electric field. 4. Moving electrical charge (current) produces a magnetic field.

Maxwell shows mathematically that if charged particles are accelerated, that a wave must be produced, and that the wave will travel at 186,000 miles/second. The wave has two parts – an oscillating electric field and an oscillating magnetic field.

An electromagnetic wave exists when the changing magnetic field causes a changing electric field which then causes another changing magnetic field, and so on forever. These oscillating fields together form an electromagnetic wave. An electromagnetic wave will travel at the speed of light, 186,000 miles/sec.

In 1864 Maxwell proves that changes in either an electric field or magnetic field will produce an electromagnetic wave; a wave that radiates at 186,000 miles/second. Hertz’s Spark and Loop Experiment In 1888, Heinrich Hertz proved Maxwell’s theories with this experiment. Hertz said, “I don’t see any useful purpose for this invisible electromagnetic energy.”

Any time charge is accelerated, an electromagnetic wave is created. ► Van de Graph and Radios  Try AM and FM settings ► Polarized Films

First wireless communications in 1895 using Morse codes Alexander Popov sent over a distance of 600 meters Guglielmo Marconi sent messages to his brother within the grounds of his Bologna estate.

The Coherer Tube (filled with iron shavings) was the Receiver When the coherer detected a radio wave, the resistance in the tube changed causing the bell to ring. The wave was created by a distant spark.

Guglielmo Marconi obtains a patent for wireless telegraphy in 1896 In 1901, the letter ‘S’ is sent from Cornwall to Newfoundland. This proved that wireless telegraphy was possible (and fast) over long distances. Wireless Room on board RMS Olympic, the sister ship to the Titanic. Wireless technology saves 706 lives after the Titanic sinks in

Dots and Dashes are digital Voice and Music are analog ► Digital is coding a signal using a binary format, e.g. 0’s and 1’s, dots and dashes, on and off ► Analog is the process of converting a signal into a wide range of continuous values. Digital data requires a computer to decode (humans were the first computers).

Photographic picture is an analog image. There are a continuous range of hues and shades that make up the image. A digital image is made up of many pixels, each pixel having one color out of a fixed number of possible colors.

Wireless transmission of Analog Data was sought as the next big thing. (“Human Ears Listening to the Radio” – get rid of digital – the clicks and clacks) ► Transmitting dots and dashes (digital) required a human computer to decode the message. ► Sending Morse codes was slow

First radio broadcast of audio on Christmas Eve in 1906 Reginald Fessenden, Canadian Fessended commemorates this event by playing “O Holy Night” on the Violin

Data Transmission This is Amplitude Modulation (AM) Carrier Wave’s amplitude is modulated Turned into a Electromagnetic Wave Amplitude is volume and frequency is the pitch. Audible range: 20 Hz - 20 kHz Sounds travels at 700 miles/hr. Audio

► Frequency, f = cycles/second (hertz) ► c = 186,000 miles/sec. ► c = 300,000,000 meters/sec. ►  = wavelength (meters/cycle) ► c = f * ► c = f *

This is Frequency Modulation (FM). This requires greater bandwidth but it is easier to cancel out noise. Turned into a Electromagnetic Wave

First radio stations in the US ► WWJ in Detroit ► KDKA in Pittsburg ► In 1920, the results of the presidential election were broadcasted. ► “San Jose Calling” was the world's first radio station with scheduled programming in 1910 (now known as KCBS)

► AM Band kHz ► FM Band to MHz ► Stations west of the Mississippi start with a K; east of the river stations begin with W

Electromagnetic Spectrum This side of line is ionizing radiation.

Other uses of Electromagnetic waves ► Cell phones use microwave radiation ► Radar ► Microwave Ovens ► Lasers ► Global Positioning Systems ► All radio (FM, AM, short wave, CB, Amateur) ► Wireless LANS & Bluetooth ► Remote Control Devices ► X-Rays and CAT Scans ► Magnetic Resonance Imaging (MRI)

E&M Waves can: ► Carry Information in analog and digital form  Radio  Wireless pt to pt Communication ► Transmit Energy  Lasers  Microwave Ovens ► Produce images inside objects  X-Rays, Gamma Rays  MRI ► Produce light (fluorescent lighting)

Microwave Ovens Microwave Ovens use 2.45 GHz (GHz = 10 9 cycles per second)

How a Microwave Works ► Microwaves are absorbed by water, fats, and sugars (the stuff in food) ► Water is a dipole molecule with both positive and negative sides ► Water molecules constantly flip over, trying to align themselves with the changing electric field of the microwave ► As the water molecules flip over they rub against each other making heat

Transformer steps up the voltage to 2000 volts Magnetron produces the microwave Waveguide leads wave into oven cavity Screen on door blocks microwaves but not visible light.

Difference between Cell Phone and Microwave Oven ► Amplitude Power Power Cell Phone 0.1 Watts Cell Phone 0.1 Watts Microwave 1000 Watts Microwave 1000 Watts Modulation Modulation Cell phone is carrying info Cell phone is carrying info Microwave is not Microwave is not

X-Rays Electrons are accelerated through a vacuum tube, they slam into a target material. Electrons in the target atoms are excited. When the electrons relax back down into a lower energy state, they emit X-Rays.

CAT – Computerized Axial Tomography ► A narrow beam of X-rays is sent through a part of the body from many different angles. ► A narrow beam is sent out 160 times over ► Opposite the beam, a sensor reads the absorption. ► A computer reconstructs 2-D cross sectional images.