Changes

=====Radio communication=====

=====Radio communication=====

The earliest electronic communication devices functioned using radio technology. Many communication devices we know today also function through radio waves. Radio waves are [https://en.wikipedia.org/wiki/Electromagnetic_radiation electromagnetic waves]. They carry energy through repeated propagation of electric and magnetic fields. Radio waves carry a certain amount of energy and can travel over large distances. When the wave reaches the destination, the receiver gets the amount of information. We cannot see radio waves but we can detect them by building receivers that can detect them. These are called as antennae. They scan the environment for radio signals and respond when they find a signal. They detect the radio signal by the effect of the changing electrical and magnetic fields. Frequency gives a measure of how fast the radio wave is being produced and depends on the source from where the radio waves start. Different radio waves come at different frequencies and we need to build transmitters that detect them.  Sound is a pressure wave – when we produce a sound it travels by disturbing the air particles. If there is no medium, sound cannot travel. What happens when we hear something on a radio?  Originally sound is produced and then it converted into radio waves. These waves are sent and received through instruments called antennae. When your radio antennae receives this radio wave, this is converted back into sound and is played.  <br>

The earliest electronic communication devices functioned using radio technology. Many communication devices we know today also function through radio waves. Radio waves are [https://en.wikipedia.org/wiki/Electromagnetic_radiation electromagnetic waves]. They carry energy through repeated propagation of electric and magnetic fields. Radio waves carry a certain amount of energy and can travel over large distances. When the wave reaches the destination, the receiver gets the amount of information. We cannot see radio waves but we can detect them by building receivers that can detect them. These are called as antennae. They scan the environment for radio signals and respond when they find a signal. They detect the radio signal by the effect of the changing electrical and magnetic fields. Frequency gives a measure of how fast the radio wave is being produced and depends on the source from where the radio waves start. Different radio waves come at different frequencies and we need to build transmitters that detect them.  Sound is a pressure wave – when we produce a sound it travels by disturbing the air particles. If there is no medium, sound cannot travel. What happens when we hear something on a radio?  Originally sound is produced and then it converted into radio waves. These waves are sent and received through instruments called antennae. When your radio antennae receives this radio wave, this is converted back into sound and is played.  <br>

'''Use of radio waves in astronomy''' : Radio waves are also produced by many celestial objects. By detecting the radio waves that travel through the atmosphere, it is possible to construct images of the astronomical objects. Radio waves can pass through dust and gas unlike light. Radio astronomy along with optical observation is allowing us to understand the universe better.

'''Use of radio waves in astronomy''' : Radio waves are also produced by many [https://en.wikipedia.org/wiki/Celestial celestial objects]. By detecting the radio waves that travel through the atmosphere, it is possible to construct images of the astronomical objects. Radio waves can pass through dust and gas unlike light. Radio astronomy along with optical observation is allowing us to understand the universe better.

=====Telephone=====

=====Telephone=====