Science

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Author:
MichKatie
ID:
273105
Filename:
Science
Updated:
2014-05-04 07:19:54
Tags:
physics
Folders:
Physics 2
Description:
physics
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  1. How can gamma radiation be used to clean?
    • Sterilisation- kills living cells used to sterilise food and
    • surgical equipment.(Also used in radio therapy)
  2. 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.
  3. 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.
  4. 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.
  5. 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.
  6. What does fission mean?
    to break apart
  7. What kind of reaction is 
    nuclear fission?
    Chain reaction
  8. Where does nuclear fission occur naturally ?
    In the mantle
  9. What is  the critical
    mass?
    • The minimum amount of energy/fuel required to form a chain
    • reaction.
  10. Give an example of nuclear 
    fission?
    23592 U + 1 0n → 9038Sr + 14454 Xe + 210n
  11. What are the daughter nuclei?
    The two produced when the first one splits
  12. What causes the nucleus to split in nuclear fission?
    A neutron
  13. What is the substance that absorbs the neutron called?
    The fissionable substance
  14. Every time a nucleus splits how many neutrons are released?
    2 or 3
  15. What is this
    • the decay series

  16. What is produced during nuclear fission?
    • Smaller atoms

  17. What is nuclear fusion?
    • The binding of nuclei

  18. Where does nuclear fusion occur?
    • In stars

  19. What does nuclear fusion form?


    Heavier elements

  20. Does nuclear fusion need energy?
    • yes and it releases a lot of energy

  21. Does nuclear fission require energy?
    • No and it gives off a lot that is why it is used to generate electricity

  22. What is half-life?
    • the time it takes for the radioactive nuclei to halve. It can be milliseconds to millions of years.

  23. What is the mass of alpha?
    • 4

  24. What is the charge of alpha ?
    • 2

  25. What is the nature of alpha?
    • Made of 2 protons and 2 neutrons

  26. What is the penetrating power of alpha?
    • Stopped by a sheet of paper

  27. What are other properties of alpha are there?
    • strongly ionising, heavy, slow moving, 5% the speed of light
  28. What is the mass of beta?
    • 0

  29. What is the charge of beta ?
    • -1

  30. What is the nature of beta?
    • they are electrons

  31. What is the penetrating power of beta?
    • Stopped by 3mm aluminium

  32. What are the other properties of beta?
    • Particles, small, light, half the speed of light

  33. What is the nature of gamma?
    • Electromagnetic waves

  34. What is the mass of gamma?
    • 0

  35. What is the charge  of gamma ?
    • 0
  36. What is he penetrating power  of gamma ?
    • Even a thick sheet of lead only reduces its intensity

  37. What are other properties of gamma?
    • Travels at the speed of light, It is a poor ioniser

  38. Show what happens when hydrogen 3 decays by beta emission.
    •  
    • H3132He +0-1β

  39. Show what happens when lead 218 decays by alpha emission.
    • 21882Pb → 21480Hg + 42Alpha

  40. 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.

  41. 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.

  42. What is the equation for power?
    • Energy transformed (J)/ Time  (s)
  43. A lamp bulb  transforms 300000 J of electrical energy when it is on for 300s.Calculate its power.
    • 300000/300 = 100W

  44. How do you work out the Energy transferred to device  per second?
    • Energy transferred to device  per second = change in flow per second X energy transfer per unit charge.

  45. How do you work out power with current?
    • Power = current X potential difference

  46. How do you work out the charge flow?
    • charge flow = current X time
    • C=AXs

  47. Calculate the charge flowing when a current of 3 A flows for 4 seconds?
    • Q= 3x4 = 12

  48. What is direct current?
    • The current  goes round the circuit in one direct only.

  49. What is alternating current ?
    • Current repeatedly reverses its direction

  50. What is the frequency of UK mains?
    • 50Hz

  51. 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.

  52. What are cables and plugs set up in?
    • Parallel

  53. What A do fuses come in?
    • 3A, 5A and 13A

  54.  How do you select what A  fuse to use ?
    • You choose a slightly higher fuse than the current of the appliance.

  55. What colour is the live wire?
    • Brown

  56. What colour is the neutral wire?
    • Blue

  57. What colour is the earth wire?
    • Yellow  and green

  58. Which wire is connected to  the longest 3-pin plug?
    • Earth

  59.  

    What do we use fuses and circuit breakers for?
    • To cut off  the circuit if it gets too high

  60.  

    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 it  would cut off when the appliance was turned on.

  61. Why don't appliances with plastic cases need to be earthed?
    • Because plastic does not conduct electricity so  would not become live and conduct electricity and be dangerous.

  62.  

    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.

  63. What happens when gravity pulls dust and gas together?
    • A protostar is formed

  64. What process happens in stars?
    Nuclear fusion where hydrogen change to helium

  65. How is a red giant formed ?
    • Hydrogen is used up and the star expands.

  66. What happens when the nuclear fusion reactions change again?
    • The inner core collapses. The star  becomes a white dwarf. Nuclear reactions form element up to iron.

  67. What happens when a star's nuclear fuel runs out ?
    • The star cools and becomes a black dwarf.

  68. What forms when the nuclear reactions run out and the star cools?
    • A black dwarf is formed

  69. What is formed when gravity has pulled together hydrogen atoms, gases and dust?
    • A prostar is formed

  70. What happens when the force of gravity is so huge that it keeps collapsing and drawing in surrounding matter?
    •  
    • A black hole is created

  71. Which star does nuclear fusion occur in and gravity and the force of expansion from the core are equal?
    Main sequence star
  72. Pic of star life cylce

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