Waves And Radiation Flashcards
Give the definition of wavelength
Horizontal distance between successive crests or troughs
Give the definition of period
The time it takes one wave to pass a point
Give the definition of frequency
Number of waves produced in one second
Describe a longitudinal wave and give an example
In Longitudinal waves the particles vibrate in the same direction as the motion of the wave. An example is sound waves
Describe a transverse wave and give an example
In transverse waves the particles oscillate (vibrate) at right angles to the direction of energy transfer. Ex water waves (also use light, gamma rays and x-rays)
All waves transfer…
Energy
What are the units of frequency
Hz
What are the units for period
Seconds
What are the units for wavelength
(Upside down y) something like lamda
Relationships to calculate wave speed
V=f y (upside down)
Relationships to calculate frequency
F=N/T
Relationships to calculate period
F=1/T
Draw a diagram of a wave label the crest. Trough. Amplitude and wavelength
. ^amplitude
/\/\/\/\/\————. ^
Complete the diagram showing diffraction around an object
|||
||| [|]
||| \\
||| [|] |||
What is diffraction
Diffraction is when waves ‘spread’ in a rather unusual way when they reach a gap in a barrier or the edge of an object in the path of the wave
List the detectors for each type of radiation
Radio — Aerial
Microwave — Aerial
Infra red — heat sensitive paper
Visible Light — eye
Ultraviolet — film
X-rays — photographic film
Gamma rays — photographic film
What do all the EM waves have in common? What speed do they travel at?
They are all transverse wave and travel at 3x10(8)
Put the EM spectrum in order of increasing frequency
Radio
Microwave
Infrared
Ultraviolet
X-ray
Gamma ray
List the typical sources for each type of radiation
Radio — TV
microwave — heating water and food
Infrared — remote controls (eg tv)
Visible light — seeing
Ultraviolet — sun-tan lamps
X-rays — imaging breaks/ defects in bones and at airports for scanning luggage
Gamma rays — medical tracers
Define angle of incidence
the angle that a line (such as a ray of light) falling on a surface makes with the normal drawn at the point of incidence.
Define angle of refraction
Light ray leaving a surface or boundary
When does refraction occur
Refraction occurs when waves pass from one medium to another.
Define refraction in terms of wave speed and wavelength.
When light enters a new medium the speed of the light changes.
What is the relative ionising effort of each type of radiation
Alpha particles — highly ionising
Beta particles — ionising
Gamma rays — very weakly ionising
Units of activity
Bq
Define activity
Activity is the number of radioactive atoms which disintegrate and emit radioactivity per second.
Define iodisation
Ionisation is the addition of removal of an electron to create an ion
Describe the nature of alpha particles
Alpha particles are composite particles consisting of two protons and two neutrons tightly bound together
Describe the nature of beta particles
Beta particles are high energy, high speed electrons
Describe the nature of gamma rays
Gamma rays have the smallest wavelengths and the most energy of any wave in the electromagnetic spectrum.
Natural sources of background radiation
Cosmic rays, radon gas and buildings
Artificial sources of background radiation
Nuclear power, weapons test and medical
List the applications of nuclear radiation
Medicine and electricity
Define absorbed dose
Absorbed dose is the energy absorbed per unit mass of the absorbing material
Relationship to calculate absorbed dose
D=E/M
Units of absorbed dose
Gy
What are the dangers of ionising radiation to living things
The greater the absorbed dose the greater the damage is likely to be
Describe the relative penetration and absorption of each type of radiation
Alpha gets absorbed by 10cm of air or 0.01mm of lead
Beta gets absorbed by 1m of air, 0.1mm of lead and 3mm of aluminium sheet
Beta gets absorbed by 1km of air or 10cm of lead
Relationship to calculate activity
A=N/T
What is nuclear fission
Fission is when the nucleus becomes unstable and splits into smaller nuclei and releases energy.
Relationship for equivalent does rate
.
H=H/t
Relationship for equivalent does
H=D Wr
Define equivalent does rate
equivalent does rate is the rate at which radiation is absorbed
Unit of equivalent does
H
Define equivalent does
Equivalent does is a quality which takes into account the type of radiation
State the radiation weighing factors for the different types of radiation
Alpha 20
Beta 1
Fast neutrons 10
Gamma 1
Slow neutrons 3
X-rays 1
List the annual exposure safety limits for the public and for workers in the radiation industries
Member of public 1mSv
Radiation worked 20mSv
Define half life
The time taken for a radioactive substance to half its original value
What are some of the challenges of nuclear fusion
Fusion has to happen at a very high temperature
What is nuclear fusion
Fusion is when smaller nuclei join to form a larger nuclei with the release of energy
Describe how fission is used to generate electricity
The heat produced during nuclear fission in the reactor core is used to boil water into steam, which turns the blades of a steam turbine. As the turbine blades turn, they drive generators that make electricity.
