2554085
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Mind Map by rachel8899, updated more than 1 year ago
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Created by rachel8899
over 9 years ago
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National 5 - Physics Unit 2 waves &
Radiation
- types of waves?
- Transverse- Particles
move up and down at 90
degrees to wave
direction. -examples:
water waves and
electromagnetic
spectrum
- Longitudinal- particles move
along wave direction
-examples: sound waves and
ultra sound
- What are waves?
- They are created by
vibrations and transfer energy
- They are created by
vibrations and transfer energy
- Transverse- Particles
move up and down at 90
degrees to wave
direction. -examples:
water waves and
electromagnetic
spectrum
- Electromagnetic spectrum
- Radio-Microwaves-Infrared-Visible-Ultraviolet-X rays-Gamma
- speed=3x10^8ms-1
- Radio-Microwaves-Infrared-Visible-Ultraviolet-X rays-Gamma
- Definitions
- Frequency?
- The amount of waves to pass a point in
1 second
- equation?
- f=number/time
- f=number/time
- The amount of waves to pass a point in
1 second
- wavelength?
- The length of one complete wave (lambda)
- The length of one complete wave (lambda)
- Period?
- The time taken to
produce one
complete wave
(seconds)
- The time taken to
produce one
complete wave
(seconds)
- Amplitude?
- The amount of energy carried by a wave
(measured from the mid point to peak or
trough)
- The amount of energy carried by a wave
(measured from the mid point to peak or
trough)
- Frequency?
- Diffraction?
- When a wave meets an obstacle and bends to some extent.
- When a wave meets an obstacle and bends to some extent.
- Refraction?
- change in speed of light as it
travels from one material to
another
- Angle of incidence- between the ray that is entering material and
the normal. Angle of refraction- between ray in material and normal.
Critical angle- when one ray is parallel to material the le between
other ray and normal
- In more dense materials light refracts towards normal.
In less dense materials light refracts away from normal
- change in speed of light as it
travels from one material to
another
- Radioactivity
- When is an element radioactive?
- When an elements mass number becomes too large its proton-neutron ratio
falls out of the band of stability. It begins to emit radiation in order to become
stable again
- When an elements mass number becomes too large its proton-neutron ratio
falls out of the band of stability. It begins to emit radiation in order to become
stable again
- Alpha
- Helium nucleus- 2 protons 2
neutrons -very ionising
-absorbed by paper, skin or
a few cm of air
- Polonium-210 used in smoke alrms
- Polonium-210 used in smoke alrms
- Helium nucleus- 2 protons 2
neutrons -very ionising
-absorbed by paper, skin or
a few cm of air
- Beta
- fast moving electron- ionising -absorbed by few cm of aluminium
- Strontium-90 used for thickness control
- Strontium-90 used for thickness control
- fast moving electron- ionising -absorbed by few cm of aluminium
- Gamma
- EM wave- least ionising- passes
through body -absorbed by several cm
of lead
- Cobalt-60 killing cancer cells
- Cobalt-60 killing cancer cells
- EM wave- least ionising- passes
through body -absorbed by several cm
of lead
- ionisation?
- when an
atom looses
or gains
electrons to
become
charged
- when an
atom looses
or gains
electrons to
become
charged
- Activity= the
number of
radioactive
decays each
second (Bq)
- Background Radiation
- Natural?
- Rocks Food
Cosmic Rays
- Rocks Food
Cosmic Rays
- Artificial?
- Medical treatments
Nuclear waste
Weapons testing
- Medical treatments
Nuclear waste
Weapons testing
- Natural?
- Half-life
- the time taken for half the nuclei
in a radioactive source to decay
- the time taken for half the nuclei
in a radioactive source to decay
- Precautions
- USe tongs, wear gloves, wash hands
- USe tongs, wear gloves, wash hands
- nuclear...
- fisson
- bombarding
a uranium
atom with a
slow neuron
producing
two or more
smaller
atoms, fast
neutrons,
and energy
- bombarding
a uranium
atom with a
slow neuron
producing
two or more
smaller
atoms, fast
neutrons,
and energy
- fusion
- joining two small nuclei to form
a larger nucleus releasing a
large amount of energy and no
radioactive waste. takes place
in sun and stars
- joining two small nuclei to form
a larger nucleus releasing a
large amount of energy and no
radioactive waste. takes place
in sun and stars
- fisson
- When is an element radioactive?
- Dosimetry
- Damage done to tissue depends on...
- Type of tissue type of
radiation and amount of
energy/radiation
- Type of tissue type of
radiation and amount of
energy/radiation
- Absorbed Dose
- the energy absorbed per unit mass
- can reduce it by- shielding, increasing d from
source and limiting time with source
- the energy absorbed per unit mass
- Equivalent dose
- the bio harm caused by radiation
- We need to measure
the rate of this to
prevent people from
experiencing too much
exposure in a short
period of time
- the bio harm caused by radiation
- Damage done to tissue depends on...
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