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