Sterilisation- kills living cells used to sterilise food and
surgical equipment.(Also used in radio therapy)
How is gamma radiation in maintenance ?
Detecting leaks in pipes - A detector is placed in the
liquid of underground pipes. If the count rate increases the pipe is leaking.
The radiation penetrates the pipe and ground so
can be detected on the surface.
How do doctors use gamma radiation?
Radioactive tracers - doctors use radioactive iodine to find
out if a patients kidney is blocked. A detector is placed on the patients kidneys. If the flow is
natural the reading goes up and down.
What is beta radiation used for and how?
controlling the thickness of sheet material
Beta particles are emitted through the aluminium foil to a detector. Some radiation is absorbed by the foil. The more radiation
is absorbed the thicker the material. The reading is then used to control the
thickness of the foil.
is alpha radiation used for and how?
Smoke detectors- Emits a steady stream of (mildly
radioactive americium) highly ionising particles. They ionise the air leaving
ions. the -ve ions formed are attracted
to oppositely charged electrodes. Smoke absorbs the radiation and sets off the
What does fission mean?
to break apart
What kind of reaction is
Where does nuclear fission occur naturally ?
In the mantle
What is the critical
The minimum amount of energy/fuel required to form a chain
Give an example of nuclear
23592 U + 1 0n → 9038Sr + 14454 Xe + 210n
What are the daughter nuclei?
The two produced when the first one splits
What causes the nucleus to split in nuclear fission?
What is the substance that absorbs the neutron called?
The fissionable substance
Every time a nucleus splits how many neutrons are released?
2 or 3
What is this
the decay series
What is produced during nuclear fission?
What is nuclear fusion?
The binding of nuclei
Where does nuclear fusion occur?
What does nuclear fusion form?
Does nuclear fusion need energy?
yes and it releases a lot of energy
Does nuclear fission require energy?
No and it gives off a lot that is why it is used to generate electricity
What is half-life?
the time it takes for the radioactive nuclei to halve. It can be milliseconds to millions of years.
What is the mass of alpha?
What is the charge of alpha ?
What is the nature of alpha?
Made of 2 protons and 2 neutrons
What is the penetrating power of alpha?
Stopped by a sheet of paper
What are other properties of alpha are there?
strongly ionising, heavy, slow moving, 5% the speed of light
What is the mass of beta?
What is the charge of beta ?
What is the nature of beta?
they are electrons
What is the penetrating power of beta?
Stopped by 3mm aluminium
What are the other properties of beta?
Particles, small, light, half the speed of light
What is the nature of gamma?
What is the mass of gamma?
What is the chargeof gamma ?
What is he penetrating powerof gamma ?
Even a thick sheet of lead only reduces its intensity
What are other properties of gamma?
Travels at the speed of light, It is a poor ioniser
Show what happens when hydrogen 3 decays by beta emission.
H31 → 32He +0-1β
Show what happens when lead 218 decays by alpha emission.
21882Pb → 21480Hg + 42Alpha
How do Ruther Ford's results explain our current model of atomic structure?
Atoms are mainly made of empty space so most of the alpha particles go straight through the empty space but a small amount hit the nucleus where there are positively charged protons which will deflect he alpha particles.
How doe Ford's results disprove the plum pudding theory of atomic structure?
If atoms were like the plum-pudding model half of the particles would be deflected a little but nly 1 in 8000 were deflected a lot.
What is the equation for power?
Energy transformed (J)/ Time(s)
A lamp bulbtransforms 300000 J of electrical energy when it is on for 300s.Calculate its power.
300000/300 = 100W
How do you work out the Energy transferred to deviceper second?
Energy transferred to deviceper second = change in flow per second X energy transfer per unit charge.
How do you work out power with current?
Power = current X potential difference
How do you work out the charge flow?
charge flow = current X time
Calculate the charge flowing when a current of 3 A flows for 4 seconds?
Q= 3x4 = 12
What is direct current?
The current goes round the circuit in one direct only.
What is alternating current ?
Current repeatedly reverses its direction
What is the frequency of UK mains?
How do we use an oscilloscope to measure the frequency of an alternating current?
It shows us the potential difference and how it changes over time. Produces a wave and measure wave length.
What are cables and plugs set up in?
What A do fuses come in?
3A, 5A and 13A
How do you select what Afuse to use ?
You choose a slightly higher fuse than the current of the appliance.
What colour is the live wire?
What colour is the neutral wire?
What colour is the earth wire?
Which wire is connected tothe longest 3-pin plug?
What do we use fuses and circuit breakers for?
To cut offthe circuit if it gets too high
Why is it important to use a fuse with the correct rating?
If the rating is too high it would not cut out when the circuit becomes dangerous. If it was too low itwould cut off when the appliance was turned on.
Why don't appliances with plastic cases need to be earthed?
Because plastic does not conduct electricity sowould not become live and conduct electricity and be dangerous.
How do metal cased objects become dangerous if not earthed?
If the earth wire is broken and the other wires are touching the case it can become lived and conduct electricity and cause electric shocks.
What happens when gravity pulls dust and gas together?
A protostar is formed
What process happens in stars?
Nuclear fusion where hydrogen change to helium
How is a red giant formed ?
Hydrogen is used up and the star expands.
What happens when the nuclear fusion reactions change again?
The inner core collapses. The starbecomes a white dwarf. Nuclear reactions form element up to iron.
What happens when a star's nuclear fuel runs out ?
The star cools and becomes a black dwarf.
What forms when the nuclear reactions run out and the star cools?
A black dwarf is formed
What is formed when gravity has pulled together hydrogen atoms, gases and dust?
A prostar is formed
What happens when the force of gravity is so huge that it keeps collapsing and drawing in surrounding matter?
A black hole is created
Which star does nuclear fusion occur in and gravity and the force of expansion from the core are equal?