Data Trasmission.

Infrared is used in many commonplace devices for exampe:-

• remote controls for your television
• sensors that control automatic doors in shops
• burglar alarms (detected by body heat)
• security lights (detected by body heat)

Analogue signal:-

• Analogue signals can have any value within a fixed range of values and are very similar to the sound of waves of speech or music.

Digital signal:-

• Digital signals dont vary;they only have two states - on (1) and off (0).There are no values in between.

Earthquakes:-

• Earthquakes produce shock waves which can travel inside the earth.
• They can damage buildings and cause tsunamis.These waves are called seismic waves and are detected by seismometers.
• Epiderma is the centre of the earthquake.

Earthquakes produce two types of seismic waves:-

• P waves - longitudinal waves - pass through solid and liquid - travel very fast.
• S waves - transverse waves - travel through solid…