P2 - Radiation and Life
- Created by: em198
- Created on: 30-03-14 17:30
View mindmap
- P2 - Radiation and Life
- The Electromagnetic Spectrum
- Seven radiations
- 1) Radiowaves
- e.g. Radios
- 2) Microwaves
- e.g. Telephone Masts
- 3) Infrared
- e.g. Remote Controls
- 4) Visible Light
- e.g. The Sun
- 5) Ultraviolet
- e.g. Sun Beds
- 6) X-Rays
- e.g. X-Ray Machines
- 7) Gamma Rays
- e.g. Some Stars
- 1) Radiowaves
- Contains 'packets' of energy called Photons
- Different radiations = different amounts of energy
- Intensity of beam
- Number of photons every second
- Amount of energy carried by each photon
- Higher the freq = more energy
- Seven radiations
- Intensity and Heat
- Energy arriving at a square metre of surface per second
- Depends on number of photons delivered per sec. And amount of energy each contains.
- Further you atre from the source, the lower the intensity.
- Photons spread as they travel - energy more spread.
- Some photons absorbed by substances they pass through
- Some photons are reflected and scattered
- When materials absorb radiation, they heat up
- Temp. increase depends on intensity.
- Depends on duration of exposure
- Ionising Radiation
- Some radioactive materials emit ionising gamma radiation.
- It has photons with enough energy to remove an electron from an atom or molecule to from ions.
- Ions are very reactive - may take part in other chemical changes
- Ionising Radiation
- Some radioactive materials emit ionising gamma radiation.
- It has photons with enough energy to remove an electron from an atom or molecule to from ions.
- Ions are very reactive - may take part in other chemical changes
- Ions are very reactive - may take part in other chemical changes
- It has photons with enough energy to remove an electron from an atom or molecule to from ions.
- Ultraviolet
- X-Rays
- Gamma
- Cell Damage
- Heating effect can cause damage
- Ionising radiation damage skin cells
- Ionising radiation can cause mutations in nucleus of cell - may cause cancer
- Different amounts of exposure = different effects
- Radiation Protection
- Microwave Ovens
- Used to heat objects containing water
- Metal case to reflect microwaves - prevents radiation from escaping
- Mobile Phones
- Low-intensity microwaves
- May be a correlation between usage and health problems
- Sunscreen - absorbs UV from sun, prevents skin cancer.
- Microwave Ovens
- Using Absorption
- X-Rays
- Absorbed by dense materials - show shadow pics of bones.
- Protected by lead and concrete
- Radiation from sun warms earth when absorbed
- X-Rays
- Some radioactive materials emit ionising gamma radiation.
- Ionising Radiation
- Ions are very reactive - may take part in other chemical changes
- It has photons with enough energy to remove an electron from an atom or molecule to from ions.
- Ultraviolet
- X-Rays
- Gamma
- Cell Damage
- Heating effect can cause damage
- Ionising radiation damage skin cells
- Ionising radiation can cause mutations in nucleus of cell - may cause cancer
- Different amounts of exposure = different effects
- Radiation Protection
- Microwave Ovens
- Used to heat objects containing water
- Metal case to reflect microwaves - prevents radiation from escaping
- Mobile Phones
- Low-intensity microwaves
- May be a correlation between usage and health problems
- Sunscreen - absorbs UV from sun, prevents skin cancer.
- Microwave Ovens
- Using Absorption
- X-Rays
- Absorbed by dense materials - show shadow pics of bones.
- Protected by lead and concrete
- Radiation from sun warms earth when absorbed
- X-Rays
- Some radioactive materials emit ionising gamma radiation.
- The Ozone Layer and Global Warming
- Ozone layer absorbs some UV from sun.
- Energy from UV causes chemical changes in the upper atomsphere.
- The Earth emits EM radiation into space
- Some gases in atmosphere absorb or reflect some of this radiation
- Keeps Earth warm - Greenhouse Effect
- Some gases in atmosphere absorb or reflect some of this radiation
- Increased GHG in atmos. means amount of absorbed radiation from sun increases.
- Increases temp. of Earth - Global Warming.
- Climate change
- Extreme weather conditions.
- Rising sea levels
- Increases temp. of Earth - Global Warming.
- Signals and Transimtting Information
- To create signal, info. put onto electromagnetic carrier waves.
- Wave must be moldulated to carry a signal.
- Changing carrier wave to create variation that matches the info. being transmitted.
- Pattern on variation decoded by reciever
- Original info
- Pattern on variation decoded by reciever
- Changing carrier wave to create variation that matches the info. being transmitted.
- Analogue Signals
- Varies continously
- Amplitude /frequency takes any value.
- Hard to distinguish between noise and original signal.
- Noise cannot be completely removed.
- Hard to distinguish between noise and original signal.
- e.g. Sound Wave
- Noise = hissing sound
- Digital Signals
- Sound and images
- Not continously varying
- Digital signals made up of two symbols - 1 (on) and 0 (off)
- On and Off - short bursts of waves.
- Benefits
- Transmitted signals have to be amplified at intervals to make them stronger
- Pick up noise - reduces quality of signal
- Easier to remove noise and recover original signal
- Travel long distances and recieved at higher quality than analogue.
- Info can be stored
- Transmitted signals have to be amplified at intervals to make them stronger
- The Electromagnetic Spectrum
Comments
No comments have yet been made