Definitions IGCSE

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Across
  1. 8. the joining of two smaller nuclei to form a larger nucleus
  2. 10. a spherical object which orbits a central star in a circular or near circular orbit
  3. 13. fission reaction releases neutrons which can go on to be absorbed by other nuclei which then go on to undergo fission themselves
  4. 15. a material which retains it magnetism for a long time
  5. 18. an element of the same number of protons but different number of neutrons
  6. 19. the resource will not run out
  7. 22. the time taken for one complete wave cycle to pass a point
  8. 23. number of radioactive decays per unit time (per second)
  9. 24. oscillations are perpendicular to the direction of travel of the wave
  10. 26. removal of electrons from an atom
  11. 29. the apparent increase in the wavelength of light emitted from distant galaxies which is caused by their moving away from Earth
  12. 30. joule per coulomb
  13. 32. the angle of incidence which gives an angle of refraction of 90 degrees
  14. 34. a spherical object which orbits a planet
  15. 35. wave changes direction due to a change in speed across a boundary
  16. 37. collection of dust and ice which orbits the sun in a very elliptical orbit
  17. 39. radiation from sources in the environment that are around us all the time e.g. medical sources, cosmic rays, underground rocks and gases
  18. 40. number of protons in the nucleus of an atom
  19. 41. has magnitude (or size) and direction
  20. 42. rate of work done (or rate of energy transfer)
  21. 43. collection of billions of galaxies
  22. 44. rate of flow of charge
  23. 47. time taken for the number of radioactive nuclei to halve / for the activity to halve
  24. 48. the brightness of a star at a fixed distance
  25. 49. whenever two objects interact, they exert equal and opposite forces on each other
  26. 50. the point through which the weight of an object acts
  27. 51. Consists of the sun, and eight planets which orbit the sun, situated in the Milky Way galaxy
  28. 52. energy required to raise 1kg of a substance by 1 degree celsius
Down
  1. 1. material returns to its original size when the forces are removed
  2. 2. the splitting of a nucleus into smaller daughter nuclei
  3. 3. a material which can be magnetised and demagnetised quickly and easily
  4. 4. the distance between a point on a wave and the same point on the next wave
  5. 5. all the light is reflected when travelling from a higher to lower refractive index material and when the angle of incidence is greater than the critical angle.
  6. 6. force is proportional to the extension
  7. 7. the temperature at which the average kinetic energy of the particles is zero
  8. 9. maximum height of the wave measured from the equilibrium position
  9. 11. oscillations are parallel to the direction of travel of the wave
  10. 12. has magnitude (or size) only
  11. 14. an imaginary surface representing points of a wave that are at the same point in their cycle
  12. 16. collection of billions of stars
  13. 17. remnant gamma radiation leftover from the Big Bang, which is now microwaves due to expansion and cooling of the universe
  14. 20. temperature scale where absolute zero is 0K and an increase of 1 degree celsius is the same as 1 Kelvin / T in K = T in C - 273
  15. 21. current changes direction frequently and repeatedly
  16. 25. current flows in one direction only
  17. 27. the resource is used up and cannot be used again
  18. 28. Line that shows the direction of the magnetic force on a North pole
  19. 31. number of protons and neutrons in the nucleus of an atom
  20. 33. energy transferred per unit charge
  21. 36. the beginning of the universe as a small, hot dense point which explanded outwards rapidly
  22. 38. sum of thinking distance and braking distance
  23. 45. the number of waves passing a point per unit time (per second)
  24. 46. energy transferred in Joules