P2 - Radiation and Life Flashcards
What is the electromagnetic spectrum?
A family of seven radiations, including visible light
What does a beam of electromagnetic radiation contain?
‘Packets’ of energy called photons
Complete the sentence:
The higher the frequency of an electromagnetic radiation…
…the more energy is transferred by each photon
All electromagnetic radiation travels at the same finite speed of what?
300,000km/s through space (a vaccum)
Name 3 high energy photons, in order from lowest to highest.
Ultraviolet rays, x-rays, gamma rays
Name 3 low-energy photons, in order from lowest to highest.
Radio waves, microwaves, infrared
Name all 7 types of electromagnetic radiation in order from lowest energy photons to highest.
Radio waves, microwaves, infrared rays, visible light, ultraviolet rays, x-rays, gamma rays
The general model of radiation shows how energy travels from a ______ that _____ radiation, to a _______ that ____ radiation.
- Source
- Emits
- Detector
- Absorbs
On the journey from _______ to _______, materials can _______, ____ or _________ radiation.
- Emitter
- Detector
- Transmit
- Reflect
- Absorb
Give an example of how on the journey from emitter to detector, materials can transmit, reflect or absorb radiation.
Clouds absorb and reflect the Sun’s energy, so on a cloudy day, we receive less light than on a clearer day.
Give an example of a) an emitter and b) its detector for radio waves.
a) TV transmitter
b) TV aerial
Give an example of a) an emitter and b) its detector for microwaves.
a) Mobile phone mast
b) Mobile phone
Give an example of a) an emitter and b) its detector for infrared waves.
a) Remote control
b) Television
Give an example of a) an emitter and b) its detector for light.
a) The Sun
b) The eye
Give an example of a) an emitter and b) its detector for ultraviolet rays.
a) Ultraviolet lamp
b) The skin
Give an example of a) an emitter and b) its detector for x-rays.
a) X-ray machine
b) Photographic plate
Give an example of a) an emitter and b) its detector for gamma rays.
a) Some stars (e.g. supernova)
b) Gamma ray telescope
What is the intensity of electromagnetic radiation?
The energy arriving at a square metre of surface per second
What does intensity of electromagnetic radiation depend on?
The number of photons delivered per second and the amount of energy each packet contains, i.e. the photon energy
a) Does the intensity of a beam increase or decrease with distance?
b) What does this mean?
a) The intensity of a beam decreases with distance
b) The further from a source you are, the lower the intensity.
When a material absorbs radiation, what is created?
Heat
When a material absorbs radiation, heat is created. What 2 things does the amount of heat created depend on?
- The intensity of the radiation beam
- The duration of the exposure
a) The decrease in the intensity of radiation with distance is due to what 3 factors? (HT)
b) Why would these factors combine? (HT)
c) What does this result in? (HT)
a) - Photons spread out as they travel
- Some photons are absorbed by particles in the substances they pass through
- Some photons are reflected and scattered by other particles.
b) To reduce the number of photons arriving per second at a detector
c) A lower measured intensity
What is ionising radiation?
Electromagnetic radiation with a high photon energy
What can ionising radiation do?
Break molecules into bits called ions
When molecules are broken into bits by ionising radiation, what are the resultant ‘bits’ called?
Ions
Give some examples of ionising radiation.
- Ultraviolet radiation
- X-rays
- Gamma rays
Are ions unreactive or very reactive? (HT)
Very reactive
Ions are very reactive which means? (HT)
They can easily take part in other chemical reactions
Give 3 ways in which radiation damages living cells.
- The heating effect can damage the skin, e.g. sunburn
- Ionising radiation can age the skin. It can also mutate DNA, which can lead to cancer
- Different amounts of exposure can cause different effects, e.g. high intensity ionising radiation can destroy cells, leading to radiation poisoning.
Give a way that heat radiation can damage the skin.
Sunburn
How do microwaves heat materials?
By causing the water particles to vibrate.
What could there be a health risk from with low intensity microwaves?
Of mobile phones and masts
Microwave ovens have a metal case and a wire screen in the door to do what?
Absorb ultraviolet radiation to help prevent skin cancer
Why do microwave ovens have a metal case and a wire screen in the door to absorb ultraviolet radiation?
To help prevent skin cancer