conventional telephone (1876)

- have shorter wavelength

electronical telegraph (1809)

constructed the first commercial electical telegraph in England

-pictures moving w/ halftone shades (1st true television pictures 1925)

wireless telegraphy within a a two mile (2mile) using water transmission

- poorer reception

EM Wave is a — wave

Wavelength Frequency, Energy. - Short wavelengths have — freq - long wavelengtas have — freq

1st application of radio in commercial, military and marine communications.

scan surrounding

EM signals travel as a change in frequency of radio waves

- have longer (that readily bends around buildings)

em waves propagate through free space

uses of visible light

-AM signals travel as changes in the — of radio waves

All parts of electromagnetic spectrom travel at the — speed

receive reflected signals

when directed at a substance light can knock electrons off of a substance (photo electric effect)

History of Radio/Telecommunication

Sxperimented transmission and radiation of radio f energy and proposed for telecommunication of information

low freq - — energy

- have clearer reception

-transmission of Voice over airwaves (1900)

own version of electrical telegraph. Used in another side of Atlantic Ocean.

wireless system

- started a company for development and propagation of radio com services and equipment.

radio wave propagation

sends narrow beam of micro

Light behaves as -- we can filter using polarized lenses