Flashcards
Waves
Flashcards do conjunto (38)
- 1Simple harmonic motion (SHM)- displacement from equilibrium gives rise to a restoring force
- proportional acceleration in the opposite direction to the displacement form equilibrium
a = -kx - 2Energy in SHMKinetic energy and potential energy
- 3Wave- propagation of a disturbance through a medium
- molecules are displaced and oscillate
- transfer energy and momentum - 4Mechanical wavesExample: Water waves, sound, string
Medium: require physical medium (not in vacuum)
Wave speed: determined by the properties of the medium
Disturbance: change of property from its equilibrium value - 5Electromagnetic waves (EM-waves)Examples: Light, radio waves, X-rays
Medium: can propagate in vacuum and various physical media
Wave speed: in vacuum - c=3x10^8m/s
Disturbance: oscillating values of electric and magnetic fields - 6EM-Waves magnitudes
- 7DisplacementA actor to the position of a point in a medium form the equilibrium position of the point.
- 8Amplitude, AThe maximum displacement.
- 9CrestA point of maximum positive displacement.
- 10TroughA point of maximum negative displacement.
- 11Wavelength, landathe length of a full wave from displacement versus distance graph
- 12Frequency, fnumber of full wave per second in hertz (Hz) - f=1/T
- 13Period, Ttime taken for one full wave to pass by - displacement-time graph - T = 1/f
- 14Intensity, Ipower transferred per unit area by a wave
I is proportional to A^2
uniform emitting source = I ∝ 1/d^2 - 15Wave speed, vspeed at which a crest moves past an observer at rest in the medium
v = f(landa) - 16Transverse waves- displacement of the medium is at right angle to the direction of wave movement/energy transfer
(EM-waves) - 17Longitudinal wavesdisplacement of the medium is parallel to the direction of the wave movement/energy transfer (sound, p-waves)
- 18Raya line indicating the direction of energy transfer of a wave
- 19Wavefronta surface at right angles to rays is called a wavefront, all points on a wavefront have the same phase - drawn trough crests
- 20Reflectionangle of incidence - between incident ray and normal to the surface - is equal to the angle of reflection
incident, reflected ray and normal are in the same plane - 21Reflection of pulses- Fixed end: pulse inverts - Newton's third law
- Free end: no inversion - 22Refraction - from one medium into another- v changes, f stays constant ⇒ Snell's law
- into more dense - towards normal
- into less dense - away from normal
n=c/v - 23Toal Internal reflection- higher refractive index to lower refractive index
- refracted angle 90° = critical angle of indecent ray
- no refraction after critical angle on reflection - 24Diffraction- aperture bigger than wavelength = little diffraction
- aperture equal or smaller = more diffraction - 25Principle of Superposition2 waves (of the same kind) meet, the resultant displacement is the sum of the individual displacements
- 26Destructive interferencewaves cancel each other out
path difference = (n+0.5)landa - 27Constructive interference- two waves meet crest-to-crest
path difference = n(landa) - 28Interference pattern from 2 sources- coherent pair of sources
- pattern equally spaced maxima/equal intensity
- maxima minima depend on path difference
∆s (separation of two consecutive max/min) = (landa) x (distance to screen) / d - 29Interference pattern from 1 sourceintensity
central maximum
angular width
- 30Polarised waveits displacement remains always in a single plane - transverse waves only
- 31Polariserpiece of plastic only transmitting the component of the electrical field parallel to polariser
1. polariser I = Io/2 - 32Malus' lawI = Iocos^2(0)
- 33Polarisation by reflection- light with electric field parallel to surface is reflected more efficiently ⇒ reflected light mainly horizontally polarised (e.g. water)
- 34Standing waves- two identical waves travelling in opposite directions meeting and superposing
- line stays in the same place with only amplitude changing
- pattern does not move to left or right
- always zero displacement = nodes - 35Standing waves on stringsL (length)= no of half waves (1st, 2nd, ... harmonic) x landa/2
- 36Standing waves in pipes: Open-open pipesL (length)= no of half waves (1st, 2nd, ... harmonic) x landa/2
- 37Standing waves in pipes: closed-open pipes- node at closed end
- antinode at open end
L = no of quarter waves (1st, 2nd, ... harmonic) x (landa)/4 - 38Travelling and standing waves- standing waves to not transfer energy
- standing waves do not have constant amplitude (compare node and antinode)
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- International Baccalaureate Physics (Oscillations and waves) FlashCards sobre Waves, criado por Jonas Schlicht em 08-04-2016.
- Criado por
- Jonas Schlicht
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