Waves
- Created by: Sophie Perrett
- Created on: 14-12-13 13:55
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- Waves
- Microwaves
- Wavelengths: 1mm-30cm
- Cooking: Water and fat molecules vibrate more, kintetic energy increases, conduction
- Communicating
- The transmitter and reciever-line of sight
- Aerials normally on high buildings
- Satellites
- The signal form earth is recieved, amplified, re-transmitted back to earth from the satellites
- They work becasues there's no onstructions in space
- Signal strength for mobile phones can change a lot over short distances
- Don't show much diffraction
- Adverse weather and water scatters signals
- The curvature of earth limits line of sight so transmitters have to be high up or close together
- Interfere
- The transmitter and reciever-line of sight
- Pass through ionsphere
- Radio waves
- Refracted and reflected by earth atmosphere
- Less refraction at higher frequencies
- Interference is reduced if digital signals are used
- DAB eliminates interference
- Same freq can be used by other radio stations
- too far away and wont interfer
- But in unusual weather conditions waves can travel further and interfer
- Radio waves are refelcted from the earth ionsphere- total internal reflection
- Water reflects, land doesnt
- Recieved from aerials not in line of sight
- Problems with communication
- Diffracted when they meet obstruction
- Slightly divergent
- Refracted and reflected by earth atmosphere
- EArthquake waves
- P waves longitudinal pressure waves. Speed 5km/s and 8km/s. Travel through SOLIDS and LIQUIDS
- S-waves are transverse, 3km/s-5.5km/s. Can only pass through SOLIDS
- Microwaves
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