Referat engleza Radio-ul

Everyone like radio, recognize ,we like to listen music ,shows and others.Through radio we are informed.So,it is a very good source.But what radio represents in general?Who invented this magical machine? Let’s talk about it.
  
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 or phase. 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.
 
The credit of inventing the radio goes to a number of researchers. The names of Guglielmo Marconi, Nikola Tesla, Alexander Popov, Sir Oliver Lodge, Reginald Fessenden, Heinrich Hertz, Amos Dolbear, Mahlon Loomis, Nathan Stubblefield and James Clerk Maxwell can be included.

1. Introduction: Who invented radio?
2. How radio works?
3. Bibliography