what is the strong nuclear force
a force which holds nucleons together inside the nucleus
what are the properties of the nuclear force
- it is a short range force acting over a nuclear distances
- it is independant of charge
- it can be attractive or repulsive
what is energy
the kinetic energy gained by an electron when it is accelerated through a p.d. of one volt
what is the mass defect of a nucleus
the difference between the mass of the nucleus and the total mass of its nucleons
how does the mass defect occur
it occurs when the nucleons are combined to form the nucleus as some of their mass is converted to energy
what is the binding energy
the energy that must be applied (the work that must be done) to separate a nucleus into non-interacting nucleons
what is fission
the splitting of large unstable nuclei to form smaller ones
what is fusion
the combining of two smaller nuclei to create a larger one
what is the basic principle behind nuclear reactors
they generate heat from nuclear fission so that water can be converted to steam
what is the critical mass in a fuel rod
the minimum mass of fissile material (fuel) required to sustain a chain reaction
what are safety features of nuclear reactors
- the reactor core is made of thick steel
- fuel rods and control rods are remotely controlled
- there is an emergency shut down system
- building is designed with thick concrete walls
what are the 3 categories for disposal of radioactive waste
high level - waste is placed in cooling ponds for up to a year, they are then sealed in lead containers and stored in cabins underground
intermediate level - sealed and covered in concrete and stored in concrete buildings or buried underground
low level - sealed in metal drums and buried underground
what are the advantage of fusion over fission
- greater power output per Kg
- raw materials are more readily available and cost less
- greater number of radioactive substances produced directly
what observations were made in rutherfords alpha scattering experiment
- most alpha particles passes straight through the foil
- a small number of particles were deflected between 0 degrees and 90 degrees
- an even smaller number of particles were deflected through an angle greater than 90 degrees
what is the least distance approach
the minimum distance an alpha particle approaches a nucleus before repelling back, used to estimate the maximum upper limit of the nuclear radius
what are the different types of radiation
alpha
beta minus
beta plus
gamma radiation
what is the intensity of a wave
energy per second (power) passing through a unit area
what is radioactive decay
when an unstable nucleus emits ionising radiation, causing a structural change in the nucleus
what is alpha decay
when a nucleus emits an alpha particle
why does gamma radiation occur
to de-excite a nucleus which has been left in an excited state (usually after alpha or beta radiation) by emitting gamma ray photons
what is background radiation
radiation present in the atmosphere they can be artificial or natural
what are uses of radioactive decay
- to monitor the thickness of metals
- in radiotherapy
- as medical tracers
- detecting leaks in pipes
- radio carbon dating
what is uranium- lead dating
it is a radiometric technique used to determine the absolute age of ancient rocks and minerals (1 million to over 4.5 billion years old) by measuring the decay of radioactive uranium isotopes into stable lead isotopes
what do radioisotopic power systems do
they are designed to transform heat energy released from the decay of an isotope into electrical power
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3- quantum phenomena49
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11- materials28
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6+7 forces in equilibrium + on the move18
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Waves and optics89
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8- newtons laws of motion6
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9- forces and momentum10
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10- work, energy and power10
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circular motion10
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19- thermal physics19
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18- simple harmonic motion27
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fields97
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20- gases22
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nuclear physics31
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turning points27
