radio waves

how are radio waves produced?

alternating current in electric circuit

1. electrons oscillate produce EM waves

   • in transmitter

2. radio waves transfer electricity

3. radio waves absorbed by conductor

   • causes electrons in receiver to oscillate

   • create alternating current

     • frequency produced = alternating current frequency

how is information passed through radio waves?

• information coded into wave before transmission

• decoded when received

where are radio waves used?

• television and radio systems

• microwaves

how are radio waves ideal for communications?

• transmitted easily through air

• do not cause damage if absorbed by the human body

• can be reflected to change direction

what is the wavelength of radio waves?

longer than 10cm

what is the advantage of long-wave radio waves (1-10km)?

• can be received long distances from transmitter

  • wavelengths diffract around curved surface of Earth

  • wavelengths diffract around hills, into tunnels, etc.

radio signals can be received when the receiver isn’t in the line of sight of the transmitter

what is the advantage of short-wave radio signals (10m-100m)?

• can be received long distances from transmitter

  • reflected from ionosphere

what radio signals do Bluetooth use?

• short-wave radio waves

• send data over short distances between devices without wires

what radio signals do TV and FM radios use?

• very short-wave radio waves

  • to get transmission, must be in direct sight of transmitter

  • signal doesn’t bend / travel far through buildings