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Flashcards

Physics - Waves

Olivia Zdzylowski Physics A-Level Inglês 57 flashcards

Physics - Waves

Flashcards do conjunto (57)

  1. 1What are the 2 types of wave? What are their differences?1. Mechanical - need a medium to travel through.
    2. Electromagnetic - able to travel through a vacuum (don't need a medium to travel).
  2. 2What is the difference between transverse and longitudinal waves?Longitudinal = direction of wave vibration is parallel to the direction of travel.
    Transverse = direction of vibration is perpendicular to the direction of travel.
  3. 3What is displacement?Distance and direction moved from the equilibrium position.
  4. 4What is amplitude?The maximum displacement from equilibrium position. (Height of wave).
  5. 5What is wavelength?Distance in metres between the same point on two successive waves.
  6. 6What is frequency?The number of cycles per second, measured in hertz (Hz). f=1/T.
  7. 7What is period?Measured in seconds, and is the time taken for one wave to be completed. T=1/f.
  8. 8What is the wave equation?Wave speed = Frequency x Wavelength
    c = fλ
    (m/s = Hz x m)
  9. 9What is the speed of light?3x10^8 m/s
  10. 10What is phase difference?Where a given point on one wave lags behind the exact same point on another wave.
  11. 11What is the equation for phase difference? What is this measured in?2πd/λ
    Measured in pi radians or degrees.
  12. 12What is the difference between: In phase Antiphase Out of phase?In phase = Whole numbers of wavelengths.
    Antiphase = Difference of 1/2λ, 180 or πrad.
    Out of phase = Difference of 1/4λ, 90 or 270 degrees or π/2 rad.
  13. 13How do you convert degrees to radians?degrees x 2π/360
  14. 14How do you convert radians to degrees?radians x 360/2π
  15. 15What is the order of the EM spectrum, and in which direction does wavelength and frequency increase?Radio, Microwave, Infrared, Visible, Ultraviolet, X-rays, Gamma.
    Wavelength increases <-- (Red = Longest)
    Frequency increases --> (Highest = Violet)
  16. 16What is the wavelength of gamma rays, and what are their applications?Wavelength -16 to -11
    Applications: Medicine (Sterilise medical equipment, and destroy tumours), and in diagnostic imagery.
  17. 17What is the wavelength of x-rays and what are their applications?Wavelength -14 to -10
    Applications: Medicine (diagnosis and therapy), and industry (detect faults in metals and study crystal structures).
  18. 18What is the wavelength and applications of ultraviolet rays?Wavelength -10 to -8
    Applications: Stimulates vitamin D production in skin, and makes some materials fluoresce (detects forged notes and used in fluorescent lamps).
  19. 19What is the wavelength and applications of visible light?Wavelength 4-7x10^-7
    Applications: Creates visual image in brain, detected by chemical changes in photographic film, electrical charges on CCD's of cameras and essential for photosynthesis of plants.
  20. 20What is the wavelength and applications of infrared rays?Wavelength -7 to -3
    Applications: Heating, cooking and thermal imagery.
  21. 21What is the wavelength and applications of microwaves?Wavelength -4 to -1
    Applications: Energy transferred to water molecules to cook food, used in mobiles and satellites.
  22. 22What is the wavelength and application of radio waves?Wavelength -3 to 5
    Application: Groups of large radio telescopes can detect faint sources in space.
  23. 23What is the relationship between the angle of reflection and the angle of incidence?Angle of incidence = Angle of reflection
  24. 24What does the reflection of water waves look like?At a boundary, some waves will be reflected back:What does the reflection of water waves look like?
  25. 25What are wave fronts and what does the distance between each one represent?Wave fronts are leading edges of waves (crests) and the distance between them represents wavelength.
  26. 26What are the 2 equations for Snell's Law?n1Sinϴ1 = n2Sinϴ2
    1n2 = Sinϴ1 / Sinϴ2
  27. 27What does the refractive index represent? What is the equation for RI from one medium to another?The RI is a ratio of speeds.
    med1 to med2 = Speed med1 / Speed med 2
  28. 28What does the ratio of speeds represent?Ratio of speeds = ratio of incident angle and refracted angle.
  29. 29How do you work out the critical angle when using the medium of air?SinC = 1/n
    n = 1/SinC
  30. 30What are the 2 types of lenses?Convex and Concave
  31. 31What is: Principal Axis Focal Length Focal Point?Principal Axis = Horizontal line through centre of the lens.
    Focal Length = Distance between the centre of the lens and the focal point.
    Focal Point = Point where rays meet to form an image.
  32. 32What is the power of a lens equation?Power (Dioptres) = 1/Focal Length (m)
  33. 33What is the rule of combining lenses?Pc = P1 + P2 + P3...
  34. 34How do you draw a ray diagram for a convex lens?1. Draw a line straight through the centre of the lens.
    2. Draw a line parallel to the axis up to the centre, then through the focus.
    3. Draw a line through the focus to the centre of the lens, then parallel to the axis.
  35. 35How do you draw a ray diagram for a concave lens?1. Draw a line parallel to the axis up to the centre of the lens, then reflect back through the focus on the same side.
    2. Draw a line through the centre of the lens undeflected.
  36. 36What is the difference between the focal length of converging and diverging lenses?Converging have +ve focal length. (Real)
    Diverging have a -ve focal length. (Virtual)
  37. 37What is the lens equation?1/u + 1/v = 1/f
    u = object distance
    v = image distance
    f = focal length
  38. 38What are the 3 things that define an image produced?1. Virtual or real.
    2. Diminished or magnified.
    3. Inverted or erect.
  39. 39What is the magnification equation?Magnification = Image Height / Object Height
    M = V / U
  40. 40What is the rule for image and object heights (being positive or negative)?If the object/image is above the axis, its +ve, if the object/image is below the axis, its -ve.
  41. 41When is light polarised?Light is polarised when oscillations occur in a single plane. They are unpolarised if the oscillations occur in many planes.
  42. 42What is: Vertically polarised light Horizontally polarised light?Vertically = only light in the vertical plane passes through.
    Horizontal = only light in the horizontal plane passes through.
  43. 43What happens to polarising filters when you turn them?At 90 and 270 degrees to each polarise light completely, making it dark.
    At 180 and 360 degrees, its light as they line up to each other.
    Anything in between is a different level of polarisation, a different level of light.
  44. 44What is the pulse-echo technique?Pulse-echo is where sound is reflected from an object to measure the distance to the object.
  45. 45What is the pulse-echo technique equation?Distance = Speed x Time
    (Time is divided by 2 because it has travelled there and back)
    So: x = vt/2
  46. 46What is superposition?The adding or subtracting of waves - interference.
  47. 47What is the rule of superposition?When 2 or more waves meet at the same type meet at a point, the resultant displacement of the oscillations is the vector sum of the individual displacements of waves.
  48. 48What are the 2 types of interference?Constructive and destructive.
  49. 49What are the properties of constructive waves?- In phase
    - Amplitude doubled
    - Distance travelled by waves from both speakers is the same (either 0 or whole numbers of wavelengths).
  50. 50What are properties of destructive interference?- Out of phase
    - Distance travelled by waves from both speakers are exactly out of phase, and the waves cancel out.
    - Path difference of 1/2, 1 1/2, 2 1/2λ.
  51. 51What are the 3 rules/conditions for there to be interference?1. Waves must be of the same type.
    2. Sources must be coherent (have the same frequency and wavelength to maintain a constant path difference).
    3. Similar amplitudes of the waves at the point of superposition.
  52. 52How does a CD player work?A laser gives out light.
    There are bumps in the CD.
    If there are no bumps, the waves are in phase, as they all have the same path length.
    If there are bumps, if the height of the bump is 1/4λ, the path difference becomes 1/2λ.
    When waves constructively interfere, the output is 1 and destructively is 0.
  53. 53How are stationary waves formed? (4 ways)1. Waves travel in both directions along a wire.
    2. Waves are being reflected.
    3. Waves superpose/produce nodes + antinodes.
    3. Nodes are produced when waves are 180 degrees out of phase (antiphase).
  54. 54What are the standing wave patterns in strings?λ1 = 2L/1
    λ2 = 2L/2 or L
    λ3 = 2L/3
    λ4 = 2L/4 or L/2
    f1 = v/λ1
    f2 = 2f1
    f3 = 3f1    What are the standing wave patterns in strings?
  55. 55What is the standing wave patterns in an air column?λ1 = 4L
    λ2 = 4L/3
    λ3 = 4L/5
    λ4 = 4L/7
    f1 = v/λ1
    f2 = 3f1
    f3 = 5f1    What is the standing wave patterns in an air column?
  56. 56What are the patterns of standing waves in an air column open at both ends?λ1 = 2L
    λ2 = L
    λ3 = 2L/3
    f1 = v/λ1
    f2 = 2f1
    f3 = 3f1    What are the patterns of standing waves in an air column open at both ends?
  57. 57What are the 3 differences between standing and travelling waves?1. Travelling waves transfer energy in the direction of travel, whereas standing waves store energy within each vibrating particle.
    2. Amplitude of oscillations is constant in travelling waves, but varies in standing waves, amp=highest @ nodes, lowest @ antinodes.
    3. Travelling waves adjacent particles have different phase relationships, but standing waves adjacent particles have constant phase relationships.

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A-Level Physics FlashCards sobre Physics - Waves, criado por Olivia Zdzylowski em 15-01-2017.
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