G9 Wave Model - How Radio Works

Gapfill exercise

Enter your answers in the gaps. When you have entered all the answers, click on the "Check" button.

   aerial      alternating      amplifier      amplitude      audio      Bluetooth      boosted      brightness      carrier      cells      demodulator      electrical      frequency      loudspeaker      modulate      noise      pressure      radio      tuning      voltage   
An electric current flowing back and forth very quickly is called an current.

Sound waves typically ahve a frequency of about 1kHz. This is the frequency AF. Radio waves have a much higher frequency - perhaps 1MHz - knowns as frequency RF.

In a microphone, the varying causes a varying .
The RF oscillator creates high-frequency AF to produce the radio waves. The steady stream of waves is called the . The AF waves are used to (vary) the of the carrier. The modulated wave is boosted by the and then sent to the .

In the receiving aerial, the incoming waves generate signals. This is a mixture of all the frequencies of all the radio circuits in the area. The circuit selects the frequency of one carrier. The removes the RF carrier leaving only the AF signal. These are by the amplifier and sent to the which produces the sound.

Amplitude modulation AM is where the of the carrier wave is varied by the audio frequency waves.
Frequency modulation FM is where the of the carrier wave is varied by the audio waves, and this is used in higher-quality systems. FM is less affected by electrical interference, called .

Other uses of radio waves.
TV pictures are transmitted with radio waves. The TV camera breaks down each picture into many narrow strips. Information about the and colour are used to modulate the carrier.
Mobile phones use transmitting aerials and receiving aerials. The areas between the masts are called .
technology uses radio waves to link items such as a mouse or printer to your computer without wires.