physics

• what is a progressive wave?

  • transfer of energy via a series of oscillations with no net movement of the matter.
• all waves undergo:

  • reflection
  • refraction
  • diffraction
  • interference
• longitudinal waves?

  • particles oscillate parallel to the direction of the wave
  • example: sound wave & p wave
• define a transverse waves

  • particles oscillate perpendicular to it's direction of travel
  • example: electromagnetic waves & s waves
• displacement?

  • distance moved in a stated direction from rest position
• amplitude?

  • maximum distance moved by a point on a vibrating body or wave measured from it's equilibrium position.
• frequency?

  • number of wavelengths passing a point per unit time
• wavelength?

  • distance between a point on a wave & the equivalent point on the adjacent wave
  • e.g peak to peak
• define wavespeed?

  • the speed which the waves travel through the medium
• time period?

  • the time for one complete oscillation/cycle of the wave.
• equation that links wavespeed, wavelength and frequency?

  • v = f x λ
• derivation from 1st principle?

  • f = 1/T
  • v = s/t
  • = λ/T
  • = λ x 1/T
  • v = f x λ
• how do particles move?

  • particles move up and down, not with the wave and as the wave travels the particles go up
• what is a phase?

  • how far through it's cycle a point on a wave is expressed as an angle.
• what is phase difference?

  • how much a point on a wave lags or leads another in it's cycle expressed as an angle.
• what is antiphase?

  • when 2 particles on a wave λ/2 apart have a phase difference of π rads.
• scalar quantity

  • has magnitude & no direction
• vector quantity

  • has both magnitude and direction
• newtons 1st law

  • an object will remain at a constant velocity or at rest unless acted upon by a resultant force
• newtons 2nd law?

  • f = ma, resultant force is directly proportional to acceleration
  • f = the rate of change of momentum
• newtons 3rd law

  • if object a exerts a force on object b, object b exerts a force that is opposite in direction and equal in magnitude and of the same type.
• 3 ways drag can increase

  • speed increases
  • surface area increases
  • viscosity of the air increases
• definition of unpolarised light?

  • transverse waves whose oscillations are perpendicular to the direction of wave travel and have multiple possible directions of oscillation
• polarised light?

  • plane polarised light is with only one direction of oscillation
• how do you polarise light (3 ways)

  • scattering of light
  • reflection
  • polarizing filter
• difference between red light and blue light (w/ air particles)

  • red light doesn't scatter off of air particles but blue light does
• definition of wavefront?

  • the point of a 3D wave in phase
• optically less dense --> more dense medium

  • wavespeed reduces
  • wavelength reduces
  • frequency same
• optically more dense --> less dense medium

  • wavespeed increases
  • wavelength increases
  • frequency same
• what is the refractive index of air and other?

  • air = 1
  • other than air >1
• definition of a critical angle?

  • being the angle of incidence where the angle of refraction = 90°
• what is total internal reflection?

  • any angle greater than the critical angle
• what is superposition

  • when 2 (or more) waves meet in space, the resultant instantaneous displacement can be found from the sum of their individual displacements at that point
• what is the condition for reinforcement?

  • waves in phase
• what is destructive interference?

  • occurs when 2 waves arrive at a point in space in antiphase with each other cancelling out each other
• what is constructive interference?

  • occurs when 2 waves arrive at a point in space completely in phase reinforcing each other
• when will a stable and predictable interference pattern form?

  • if the 2 sources have the same wavelength & frequency are coherent
• what is coherence?

  • the 2 sources have a constant phase difference
• what is phase difference?

  • the difference in the number of phases the 2 waves have gone through in reaching the point, expressed as an angle in radians, i.e how much one lags or leads the other expressed as an angle
• what is path difference?

  • the difference in the path travelled by the two waves, expressed in terms of the wavelength