P2 - Radiation and Life
- Created by: Laura0_0
- Created on: 23-05-17 16:14
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- Radiation and Life
- Electromagnetic spectrum
- Radiowaves
- Least Energy
- Low frequency
- Microwaves
- Infrared
- Visible light
- Ultraviolet
- X-ray
- Gamma Rays
- Most energy
- High frequency
- Ionising
- Noon-ionising
- Radiowaves
- Ionisation
- Ionisation can occur to living cells
- The damage to DNA molecules can cause mutations
- Can lead to cancer
- The damage to DNA molecules can cause mutations
- Ionisation can occur to living cells
- Transfer of EM radiation
- EM radiation is emitted from a source
- The frequency of thermal radiation increases with temperature
- All types of EM radiation travel in a vacuum at 300,000 km/s
- It is transmitted, reflected or absorbed
- Transmitted = keeps on going
- Reflected = it bounces back
- Absorbed
- Objects that absorb radiation are called DETECTORS
- eg. Eyes are light detectors
- Objects that absorb radiation are called DETECTORS
- EM radiation is emitted from a source
- Intensity
- Total energy = number of photons x energy per photon
- Intensity is how much energy arrives at each square metre of surface
- It is measured is Watts per square metre
- Decreases with distance from the source
- The beam spreads out
- The beam is partially absorbed as it travels
- Uses of EM radiation
- Microwaves
- Cause particles to vibrate, heating them up
- Microwave ovens
- More powerful ovens produce higher intensity radiation
- Metal cases and screens to absorb and reflect radiation
- Protects body cells from heating effect
- Mobile phones
- Microwaves send signals between mobile phones and phone masts
- Emit low intensity radiation
- Less of a heating effect
- X-rays
- Absorbed by more dense materials
- Create 'shadow pictures' of bones
- Pass through les dense materials
- radiographers protected by lead aprons and concrete screens
- Create 'shadow pictures' of bones
- Pass through les dense materials
- Absorbed by more dense materials
- Ultraviolet
- Sunburn
- Skin cancer
- Sunbathing
- Gives you a tan
- Necessary for the body to make vitamin D
- Sunburn
- Communications
- Radio Waves
- Sending information on Earth
- Don't get absorbed by Earth's atmosphere
- TV and Radio transmitions
- Very short wavelengths
- Sending information on Earth
- Microwaves
- Sending information to satellites
- Pass easily through the atmosphere
- Sending information to satellites
- Infrared and Light
- Optical fibres
- waves are reflected off the sides of a glass core
- Glass doesn't absorb much radiation
- the signal doesn't weaken
- Optical fibres
- Signals
- Analogue
- Varying amplitude
- Weaken and pick up noise
- Digital
- On or Off
- Can be regenerated to remove the noise
- Can send more information
- Information can be stored and processed by computers
- Information I converted to electrical signals before its transmitted
- It is superimposed onto a carrier wave
- Analogue
- Radio Waves
- Microwaves
- Earth's atmosphere
- Earth absorbs EM radiation from the sun
- Earth emits infrared (heat) radiation
- Lots of this radiation is absorbed by atmospheric gases
- The gases re-radiate heat back to Earth
- This keeps the Earth warm enough for life
- The gases re-radiate heat back to Earth
- Lots of this radiation is absorbed by atmospheric gases
- Ozone
- Ozone absorbs harmful UV radiation, protecting us
- The ozone splits into O2 and O
- These can react to form ozone again
- The ozone splits into O2 and O
- O3
- Ozone absorbs harmful UV radiation, protecting us
- Electromagnetic spectrum
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