Презентация к уроку английского языка "The radio invention" -

What is radio?
Radio is the transmission of signals by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic
fields that pass through the air
and the vacuum of space.
Information is carried by systematically
changing (modulating) some property
of the radiated waves, such
as amplitude, frequency, phase,
or pulse width. When radio
waves pass an electrical conductor, the
oscillating fields induce an alternating current
in the conductor. This can be detected and transformed into sound or other signals that carry information.

Who has invented radio?
In 1895 Alexander Stepanovich Popov built his first radio receiver, which contained a coherer. Further refined as a lightning detector, it was presented to the Russian Physical and Chemical Society on May 7, 1895. A depiction of Popov's lightning detector was printed in the Journal of the Russian Physical and Chemical Society the same year. Popov's receiver was created on
the improved basis of Lodge's
receiver, and originally
intended for reproduction
of its experiments.

Who is Popov?
Alexander Stepanovich Popov (1859-1906)
was a Russian physicist who first demonstrated the practical
application of electromagnetic (radio) waves, although
he did not apply for a patent for his invention.
Born in the village Turinskiye Rudniki
(now Krasnoturinsk, Sverdlovsk Oblast)
in the Ural mountains as the son of a priest,
he became interested in natural sciences
early in his youth. His father ensured
that Alexander received a good education
at the seminary at Perm, and later studying physics at the St. Petersburg university. After graduation in 1882 he started to work as a laboratory assistant at the university. However, due to the bad funding of the university he changed to a teaching job at the Russian Navy's Torpedo School in Kronstadt on Kotlin Island.
Beginning in the early 1890s he conducted experiments along the lines of Heinrich Hertz's research. In 1894 he built his first radio receiver, which contained a coherer.
Further refined as a lightning detector, it was presented to the Russian Physical and Chemical Society on May 7, 1895—the day has been celebrated in the Russian Federation as "Radio Day“.

Radio day.
Radio Day is a commemoration of the development of radio in Russia. It takes place on May 7, the day in 1895 on which Alexander Popov successfully demonstrated his invention.
Radio Day was first observed in
the Soviet Union in 1945,
on the 50th anniversary of
Popov's experiment, and some
four decades after his death.
Radio Day is officially marked in Russia
and Bulgaria.