radiation Flashcards
what is alpha radiation?
what particles does it consist of?
what is its charge?
what is it blocked by?
ionising strength?
penetrating strength?
alpha radiation is a helium nucleus and consists of 2 protons and 2 neutrons giving a positive charge. It is blocked by a sheet of paper or a few cm of air and its ability to ionise is strong but it’s penetration power is weak.
what is beta radiation?
what particles does it consist of?
what is its charge?
what is it blocked by?
ionising strength?
penetrating strength?
beta is a fast moving electron which is ejected from a nucleus of an atom when a neutron splits into a proton and electron. It has a negative charge. It is blocked by about 3mm of aluminium and its ability to ionise is weak
what is gamma radiation?
what particles does it consist of?
what is its charge?
what is it blocked by?
ionising strength?
penetrating strength?
Gamma has no charge as it is part of the electromagnetic spectrum it has a very short wavelength and very high energy. It is blocked by about 3 cm of lead and its ability to ionise is weak and it’s penetration power is high.
what is ionisation?
Ionisation occurs when an atom gains or loses electrons to become charged
what is decaying
A radioactive source contains unstable nuclei that decay to more stable forms by emitting radiation
what is activity?
the number of decays per second
what is half life?
the half life of a radioactive source is the time taken for the activity of the source to decrease to half of its original value or the time taken for half the nuclei in a source to decay
absorbed dose equation
absorbed dose = energy absorbed / mass of tissue
D=E/M
equivalent dose equation
equivalent dose (sv) = absorbed dose (Grays) X radiation weighting factor
H=DWr
what is the average annual background radiation in the UK?
2.2msv
what is the average effective does limit for a member of the public?
1msv
what is the average effective dose limit for a radiation worker?
20 msv
what happens during nuclear fission?
a neutron is fired at a large, unstable nucleus splitting the nucleus in two and releasing heat energy and more neutrons
what is a chain reaction?
the neutrons released from a fission reaction go on to split other nuclei and the process continues
nuclear power
we can use energy stored in atomic nuclei to generate power by using two different reactions
how do nuclear reactions work?
nuclear reactions produce heat which is used to boil water into steam. The steam turns a turbine which spins a generator producing electricity.
what is the energy change during a nuclear reaction?
nuclear - heat - kinetic - electrical
what is nuclear fusion?
two small nuclei fuse together to form a larger nucleus
what is one gray equal to?
One gray is equal to one joule per kilogram
is heat released during fission?
yes
equivalent does rate formula
H*= H/t
equivalent does rate = equivalent dose÷ time
what is weighting factor related to?
ionising strength
what is the order of particles in a nucleus in increasing size ?
electron, proton, helium nucleus
How does radiotherapy with gamma rays work?
gamma radiation has such high energy it can kill live cells
name 2 advantages of nuclear fission
- Nuclear reactors do not produce pollutants
- The fuel for nuclear reactors will last a long time
name 2 disadvantages of nuclear fission
Nuclear reactors are expensive to build and the time from deciding to build one and it being operational can be many years
*Leaks of radioactive materials can have a major impact on the surrounding environment
*Waste from nuclear reactors must be stored underground for a long time until the radiation emitted decreases.
precautions to take to avoid absorbing radiation
lift radioactive sources with forceps
wear a lead vest
distance yourself from the radioactive material
do it quickly
what can nuclear radiation be used for medically and industrially?
used to treat tumors by killing the cancer cells present in a tumour.
can sterilise medical instruments by destroying organisms on them
radiation can be concentrated in certain organs in the body and this helps a doctor to diagnose or treat a disease.
used in some detectors
background radiation?
man made :
building materials
radioactive materials used in smoke detectors
natural :
cosmic radiation from outer space
rocks and minerals like granite.
what does an atom consist of?
protons, neutrons and orbiting electrons
