2610608
Nat 5 Physics Waves
and Radiation
- Nuclear Radiation
- Atoms are made up of
protons, neutrons and
electrons
- Ionisation is when an atoms
loses or gains an electron and
becomes charged. If it loses an
electron is becomes positive and
if is gains it becomes negative
- Atoms can be ionised in many ways.
There are three main types of ionising
radiation
- Alpha
- made up of 2
protons and two
neutrons
- Helium Nucleus
- Helium Nucleus
- very slow and heavy
compared to beta and
gamma
- most ionising out of the three
- stopped by a sheet of paper
- positively charged
- made up of 2
protons and two
neutrons
- Beta
- fast moving
electron
- smaller and faster
than alpha
- produced when a
neutron decays into a
proton
- negative
- not as ionising as alpha
- stopped by
sheet of
aluminium
- fast moving
electron
- Gamma
- electromagnetic
wave
- travel at the
speed of light
3x10^8 m/s
- no mass
- no charge
- very weakly ionising
- can only be stopped with a
block of lead
- electromagnetic
wave
- Isotopes are
atoms with the
same number of
protons but a
different
number of
neutrons
- Radiation will turn
photographic film black
- Gamma can be detected
with a geiger muller tube
- Gamma can be detected
with a geiger muller tube
- Safety
- Limit time exposed
- Wear protective clothing
- Hold radiation away from face
- Hold radiation away from face
- Wear protective clothing
- Limit time exposed
- Uses of Radiation
- Radiotherapy
- Medical tracers
- alpha radiation is used in
smoke dectectors
- monitor thickness of
paper- beta
- Radiotherapy
- Dosimetry is the
measurement of the
amount of radiation
- Activity
- The number of
nuclei decaying
every second
- Measure in Becquerels (Bq)
- activity =number of decays/time
- The number of
nuclei decaying
every second
- Absorbed Dose
- The amount which
is absorbed per 1kg
of material
- Measured in Grays
(Gy)
- Absorbed Dose =
Energy/ mass
- The amount which
is absorbed per 1kg
of material
- Equivalent Dose
- Harming effect radiation
has on the body
- Measured in sieverts (Sv)
- Equivalent Dose =
Absorbed Dose x
Weighting Factor
- Weighting factor is how
dangerous the radiation is
- Higher the
Weighting factor the
more dangerous
- Found in Data Sheet
- Found in Data Sheet
- Higher the
Weighting factor the
more dangerous
- Weighting factor is how
dangerous the radiation is
- Harming effect radiation
has on the body
- Activity
- Half Life is the
amount of time it
takes for the
radioactivity of a
substance to half
- Nuclear
Fission/ Fusion
- Fission
- When the nucleus
of a large atom is
split creating two
smaller nuclei,
neutrons and a
large amount of
energy
- Can cause
chain
reaction
- Can cause
chain
reaction
- When the nucleus
of a large atom is
split creating two
smaller nuclei,
neutrons and a
large amount of
energy
- Fusion
- Occurs at very high
temperatures. Process
of joining two samll
nuclei together and
releasing a lot of
energy
- Nuclear fusion is better than
fission as it is safer, produces less
harmful waste, easy to get fuel.
However it needs very high
temperatures which is very difficult
- Nuclear fusion is better than
fission as it is safer, produces less
harmful waste, easy to get fuel.
However it needs very high
temperatures which is very difficult
- Occurs at very high
temperatures. Process
of joining two samll
nuclei together and
releasing a lot of
energy
- Fission
- Atoms are made up of
protons, neutrons and
electrons
- The Electromagnetic
Spectrum
- The elctromagnetic
spectrum is a family
of waves which are
all transverse waves
- All EM
spectrum waves
travel at 3x10^8
m/s or
3,000,00,000
m/s
- Gamma waves are used to kill cancer
and are detected by a geiger-muller
tube
- X-rays are used to take photos of
your body and are dectected by
photographic film
- Turn photographic film
black
- Turn photographic film
black
- Ultraviolet can be used to treat
acne and too much can cause
skin damage
- Visible light is separated in seven
different colours Red, Orange, Yellow,
Grean, Blue, Indigo and Violet.
(ROYGBIV)
- Red has a longer
wave length than
violet
- Visible light is detected by
our eyes and can be used
as a laser
- Red has a longer
wave length than
violet
- Infrared us heat radiation
and can be dectected by a
thermometer
- Used in medicine as heat treatment and
in industry to dry paint
- Used in medicine as heat treatment and
in industry to dry paint
- Microwaves are detected by an aerial
and is used for mobile phones
- Radio/TV waves are
dected by an aerial
and carry programmes
- Gamma has the highest frequency
and the shortest wavelength and
radio waves have the lowest
frequency and the longest wavelength
- The elctromagnetic
spectrum is a family
of waves which are
all transverse waves
- Waves
- All waves transfer energy
- Longitudinal waves vibrate in the
same direction as the direction
the wave is travelling
- Sound waves
- Sound waves
- In transverse waves the vibration
is at a right angle to the direction
the wave is travelling in
- Radio waves, Light waves,
water waves
- Radio waves, Light waves,
water waves
- Wavelength is the
distance from peak to
peak or trough to trough
- measured in metres
- Symbol- lambda
- Symbol- lambda
- measured in metres
- The amplitude of a wave is the
height of the wave from the
middle point to the peak
- units vary
- units vary
- Frequency is the measure of the
number of waves passing a point each
second or the number of waves per
second
- frequency= no. of waves/ time
- measured in hertz (Hz)
- Symbol is f
- measured in hertz (Hz)
- frequency= no. of waves/ time
- The period of a wave is the time
taken for one wave to pass a point.
- period = 1/ frequency
- Symbol is T
- measured in seconds (s)
- Symbol is T
- period = 1/ frequency
- Wave equation
- speed= frequency x wavelength
- speed= frequency x wavelength
- Diffraction is the bending
of waves round an object
- The longer the wavelength/
lower the frequency the better a
wave diffracts
- The shorter the wavelength/ the
higher the frequency the less the
wave diffracts
- The longer the wavelength/
lower the frequency the better a
wave diffracts
- All waves transfer energy
- Light
- When the speed of light changes when
it travels from one substance to another
it is called refraction
- If the light travels at an angle to
the normal the direction and the
speed changes
- If a ray is travelling from air to glass it
bends towards the normal and when it
travels from glass back to air it bends
away from the normal
- Long sightedness can be corrected
using a convex lense and short with
a concave lense
- Convex lense focuses light to
one point
- Concave lenses spread light out
- When the speed of light changes when
it travels from one substance to another
it is called refraction
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