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MichKatie
on FreezingBlue Flashcards.
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How can gamma radiation be used to clean?
- Sterilisation- kills living cells used to sterilise food and
- surgical equipment.(Also used in radio therapy)
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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.
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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.
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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.
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What
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
- alarm.
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What does fission mean?
to break apart
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What kind of reaction is
nuclear fission?
Chain reaction
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Where does nuclear fission occur naturally ?
In the mantle
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What is the critical
mass?
- The minimum amount of energy/fuel required to form a chain
- reaction.
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Give an example of nuclear
fission?
23592 U + 1 0n → 9038Sr + 14454 Xe + 210n
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What are the daughter nuclei?
The two produced when the first one splits
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What causes the nucleus to split in nuclear fission?
A neutron
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What is the substance that absorbs the neutron called?
The fissionable substance
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Every time a nucleus splits how many neutrons are released?
2 or 3
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 What is this
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What is produced during nuclear fission?
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Where does nuclear fusion occur?
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What does nuclear fusion form?
Heavier elements
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Does nuclear fusion need energy?
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- yes and it releases a lot of energy
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Does nuclear fission require energy?
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- No and it gives off a lot that is why it is used to generate electricity
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What is half-life?
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- the time it takes for the radioactive nuclei to halve. It can be milliseconds to millions of years.
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What is the mass of alpha?
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What is the charge of alpha ?
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What is the nature of alpha?
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- Made of 2 protons and 2 neutrons
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What is the penetrating power of alpha?
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- Stopped by a sheet of paper
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What are other properties of alpha are there?
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- strongly ionising, heavy, slow moving, 5% the speed of light
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What is the mass of beta?
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What is the charge of beta ?
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What is the nature of beta?
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What is the penetrating power of beta?
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What are the other properties of beta?
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- Particles, small, light, half the speed of light
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What is the nature of gamma?
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What is the mass of gamma?
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What is the charge of gamma ?
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What is he penetrating power of gamma ?
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- Even a thick sheet of lead only reduces its intensity
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What are other properties of gamma?
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- Travels at the speed of light, It is a poor ioniser
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Show what happens when hydrogen 3 decays by beta emission.
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Show what happens when lead 218 decays by alpha emission.
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- 21882Pb → 21480Hg + 42Alpha
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How do Ruther Ford's results explain our current model of atomic structure?
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- 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.
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How doe Ford's results disprove the plum pudding theory of atomic structure?
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- 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.
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What is the equation for power?
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- Energy transformed (J)/ Time (s)
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A lamp bulb transforms 300000 J of electrical energy when it is on for 300s.Calculate its power.
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How do you work out the Energy transferred to device per second?
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- Energy transferred to device per second = change in flow per second X energy transfer per unit charge.
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How do you work out power with current?
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- Power = current X potential difference
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How do you work out the charge flow?
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- charge flow = current X time
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- C=AXs
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Calculate the charge flowing when a current of 3 A flows for 4 seconds?
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What is direct current?
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- The current goes round the circuit in one direct only.
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What is alternating current ?
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- Current repeatedly reverses its direction
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What is the frequency of UK mains?
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How do we use an oscilloscope to measure the frequency of an alternating current?
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- It shows us the potential difference and how it changes over time. Produces a wave and measure wave length.
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What are cables and plugs set up in?
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How do you select what A fuse to use ?
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- You choose a slightly higher fuse than the current of the appliance.
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What colour is the live wire?
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What colour is the neutral wire?
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What colour is the earth wire?
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Which wire is connected to the longest 3-pin plug?
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What do we use fuses and circuit breakers for?
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- To cut off the circuit if it gets too high
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Why is it important to use a fuse with the correct rating?
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- If the rating is too high it would not cut out when the circuit becomes dangerous. If it was too low it would cut off when the appliance was turned on.
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Why don't appliances with plastic cases need to be earthed?
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- Because plastic does not conduct electricity so would not become live and conduct electricity and be dangerous.
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How do metal cased objects become dangerous if not earthed?
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- 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.
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What happens when gravity pulls dust and gas together?
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What process happens in stars?
Nuclear fusion where hydrogen change to helium
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How is a red giant formed ?
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- Hydrogen is used up and the star expands.
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What happens when the nuclear fusion reactions change again?
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- The inner core collapses. The star becomes a white dwarf. Nuclear reactions form element up to iron.
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What happens when a star's nuclear fuel runs out ?
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- The star cools and becomes a black dwarf.
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What forms when the nuclear reactions run out and the star cools?
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What is formed when gravity has pulled together hydrogen atoms, gases and dust?
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What happens when the force of gravity is so huge that it keeps collapsing and drawing in surrounding matter?
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Which star does nuclear fusion occur in and gravity and the force of expansion from the core are equal?
Main sequence star
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