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Wave-Particle Duality

Sally Lancaster 11 questions

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Questions in this quiz (11)

  1. 1Wave-Particle Duality Theory:
    - De Broglie said that if light, which is considered as a [blank_start]wave[blank_end], can show [blank_start]particle[blank_end] properties (photons); then things which are usually considered as [blank_start]particles[blank_end] such as [blank_start]electrons[blank_end], could be expected to show [blank_start]wave[blank_end]-[blank_start]like[blank_end] properties.
    - He came up with an equation which relates a [blank_start]wave[blank_end] property (wavelength, λ) to a moving [blank_start]particle[blank_end] property (momentum, p).
    λ = [blank_start]h[blank_end] / [blank_start]p[blank_end] = h / mv
    - The de Broglie wave of a particle can be interpreted as a "probability wave" - the likelihood of finding a particle at a p[blank_start]oint[blank_end] is directly [blank_start]proportional[blank_end] to the square of the [blank_start]amplitude[blank_end] of the wave at that point.
    - His ideas were just s[blank_start]peculation[blank_end] to start with until later experiments c[blank_start]onfirmed[blank_end] the wave nature of electrons.
    1. Awave
    2. Bparticle
    3. Cparticles
    4. Delectrons
    5. Ewave
    6. Flike
    7. Gwave
    8. Hparticle
    9. Ih
    10. Jp
    11. Kproportional
    12. Lamplitude
    13. Mpeculation
    14. Nonfirmed
    15. Ooint
  2. 2Electron Diffraction:
    - Electron diffraction is proof of the [blank_start]wave[blank_end] nature of electrons.
    - A high speed beam of electrons is generated by [blank_start]thermionic[blank_end] emission, followed by [blank_start]acceleration[blank_end] of the electrons using a cathode and anode with a [blank_start]high pd[blank_end] between them. A very [blank_start]thin[blank_end] piece of foil or some polycrystalline [blank_start]graphite[blank_end] is put in the path of the electrons. On the other side of the foil/graphite is a [blank_start]phosphorescent[blank_end] screen. Phosphor emits [blank_start]visible[blank_end] light when it is struck by electrons (i.e. phosphor atoms [blank_start]excited[blank_end] by incident electrons) so that the pattern of electrons can be seen.
    - [blank_start]Diffraction[blank_end] patterns are observed when accelerated electrons in the [blank_start]vacuum[blank_end] tube [blank_start]interact[blank_end] with the [blank_start]spaces[blank_end] between atoms in the [blank_start]foil[blank_end] or graphite. The patterns observed are [blank_start]very similar[blank_end] to those seen when high frequency EM radiation such as X-rays are shone through a thin piece of foil thus [blank_start]confirming[blank_end] that electrons show wave-like properties.
    - For maximum electron diffraction, de Broglie wavelength of electrons [blank_start]approximately equals[blank_end] the space between atoms in the foil/graphite.
    - In general, λ (de Broglie wavelength) for electrons accelerated in a vacuum tube is about the [blank_start]same size[blank_end] as electromagnetic waves in the [blank_start]X-ray[blank_end] part of the spectrum.    Image for question 2
    1. Awave
    2. Bparticle
    3. Cthermionic
    4. Dacceleration
    5. Ehigh pd
    6. Fthin
    7. Gphosphorescent
    8. Hvisible
    9. Iexcited
    10. JDiffraction
    11. Kvacuum
    12. Linteract
    13. Mspaces
    14. Nfoil
    15. Oconfirming
    16. Pvery similar
    17. Qvery different
    18. Rapproximately equals
    19. Sgraphite
    20. Tsame size
    21. UX-ray
    22. Vgamma
    23. WUV
  3. 3Changing Electron Diffraction Patterns:
    - According to [blank_start]wave theory[blank_end], the spread of the lines in the diffraction pattern increases if the wavelength of the wave is [blank_start]greater[blank_end].
    - Decreasing the accelerating voltage [blank_start]slows down[blank_end] the electrons. As λ = h / mv, if you decrease v where h and m are constant then you increase λ. Therefore you get [blank_start]widely spaced[blank_end] rings for smaller accelerating voltages and slower electrons.
    - Similarly if you use protons instead of electrons the rings will be [blank_start]closer together[blank_end] because m will be bigger (where h and v are constant) so λ will be [blank_start]smaller[blank_end] and there will be [blank_start]less[blank_end] diffraction thus resulting in the rings being closer together.
    - If the electron speed is [blank_start]increased[blank_end], the diffraction pattern circles squash together towards the middle as the de Broglie wavelength is [blank_start]reduced[blank_end] by the increased momentum.    Image for question 3
    1. Awave theory
    2. Bparticle theory
    3. Cgreater
    4. Dsmaller
    5. Eslows down
    6. Fspeeds up
    7. Gwidely spaced
    8. Hclose together
    9. Icloser together
    10. Jfurther apart
    11. Ksmaller
    12. Lbigger
    13. Mless
    14. Nmore
    15. Oincreased
    16. Pdecreased
    17. Qreduced
    18. Rincreased
  4. 4Particles Don't Show Wave-Like Properties All the Time:
    - You only get diffraction if a particle interacts with an object of about the [blank_start]same[blank_end] size as its de Broglie [blank_start]wavelength[blank_end]. E.g. a 0.058kg tennis ball travelling at 100 ms^-1 has a de Broglie wavelength of 10^-34 m. There is nothing this small for it to [blank_start]interact[blank_end] with so it [blank_start]can't[blank_end] be diffracted.
    - Electrons with a wavelength of around 1 x 10^-10 are likely to be diffracted by the a[blank_start]toms[blank_end] in polycrystalline structures.
    - A shorter wavelength gives less d[blank_start]iffraction[blank_end] effects. This fact is used in the electron m[blank_start]icroscope[blank_end].
    - Diffraction effects b[blank_start]lur[blank_end] detail on an image. If you want tiny detail in an image, you need a [blank_start]shorter[blank_end] wavelength. Light blurs out detail [blank_start]more[blank_end] than "electron-waves" do, so an electron microscope can r[blank_start]esolve[blank_end] finer detail than a light microscope.    Image for question 4
    1. Asame
    2. Bwavelength
    3. Cinteract
    4. Dcan't
    5. Eshorter
    6. Fmore
    7. Gesolve
    8. Htoms
    9. Iiffraction
    10. Jicroscope
    11. Klur
  5. 5The de Broglie wavelength of a particle, λ, is interpreted as the equivalent wavelength of a particle.Image for question 5
    1. ATrue
    2. BFalse
  6. 6Proof of Particle Nature of Electrons:
    - The [blank_start]Maltese Cross Experiment[blank_end] shows the [blank_start]particle[blank_end] nature of electrons. The electrons form a [blank_start]crisp[blank_end] shadow. This suggests that the electrons behave as particles because electrons in the path of the Maltese Cross [blank_start]do not[blank_end] get past it resulting in the [blank_start]shadow[blank_end]. If the electrons were behaving as [blank_start]waves[blank_end], the image would be [blank_start]fuzzy[blank_end] not crisp.
    - A [blank_start]bar magnet[blank_end] changes the [blank_start]position[blank_end] of the image as the electrons are [blank_start]deflected[blank_end] by the magnetic field. A beam of light [blank_start]cannot[blank_end] be deflected by a magnetic field because [blank_start]photons[blank_end] have no charge. Moving electrons are deflected because they are [blank_start]charged particles[blank_end].
    - Any apparatus which includes an [blank_start]electron gun[blank_end] relies on the fact that electrons act like particles because only charged particles can be [blank_start]accelerated[blank_end] by a magnetic field (waves have [blank_start]no charge[blank_end]).
    - Any apparatus using a bar magnet to [blank_start]change[blank_end] the position of an image relies on the fact that electrons act like particles because only [blank_start]charged[blank_end] particles can be deflected by a [blank_start]magnetic field[blank_end] (waves have no charge).    Image for question 6
    1. AMaltese Cross Experiment
    2. Bparticle
    3. Cwave
    4. Dcrisp
    5. Eshadow
    6. Fdo not
    7. Gdo
    8. Hfuzzy
    9. Iwaves
    10. Jbar magnet
    11. Kposition
    12. Ldeflected
    13. Mcannot
    14. Ncan
    15. Ophotons
    16. Pcharged particles
    17. Qelectron gun
    18. Raccelerated
    19. Smagnetic field
    20. Tno charge
    21. Ucharged
    22. Vchange
  7. 7Evidence for light as a wave:Image for question 7
    1. ADouble slit experiment (using visible light). Light diffracts from both slits and an interference pattern is observed.
    2. BThe Photoelectric effect. Light is shone on metal and if it is above the threshold frequency of the metal, electrons will be emitted from the metal.
    3. CInterference patterns. Light waves demonstrate constructive interference when the phase difference is 0°/360° and destructive interference when the phase difference is 180°.
    4. DInterference patterns. Light waves demonstrate constructive interference when the phase difference is 180° and destructive interference when the phase difference is 0°/360°.
  8. 8Evidence for light as a particle (photons):Image for question 8
    1. AThe Photoelectric effect. Light is shone on metal and if it is above the threshold frequency of the metal, electrons will be emitted from the metal.
    2. BInterference patterns. Light waves demonstrate constructive interference when the phase difference is 0°/360° and destructive interference when the phase difference is 180°.
    3. CMaltese Cross Experiment. Electrons form a crisp shadow due to not getting past the cross. Also, electrons are deflected by a bar magnet due to the fact that magnetic fields affect charged particles.
  9. 9What is the evidence for the wave-like behaviour of electrons?Image for question 9
    1. AMaltese Cross Experiment. Electrons form a crisp shadow due to not getting past the cross. Also, electrons are deflected by a bar magnet due to the fact that magnetic fields affect charged particles.
    2. BElectron diffraction. Accelerated electrons in a vacuum tube go through a thin piece of foil/graphite and spread out causing a diffraction pattern.
    3. CThe Photoelectric effect. Light is shone on metal and if it is above the threshold frequency of the metal, electrons will be emitted from the metal.
  10. 10What is the evidence for the particle-like behaviour of electrons?Image for question 10
    1. AElectron diffraction. Accelerated electrons in a vacuum tube go through a thin piece of foil/graphite and spread out causing a diffraction pattern.
    2. BThe Photoelectric effect. Light is shone on metal and if it is above the threshold frequency of the metal, electrons will be emitted from the metal.
    3. CThe Maltese Cross Experiment. Electrons form a crisp shadow due to not getting past the cross. Also, electrons are deflected by a bar magnet due to the fact that magnetic fields affect charged particles.

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Description
AS - Level Sally's Physics (Waves and Particle Nature of Light) Quiz on Wave-Particle Duality, created by Sally Lancaster on 27/04/2016.
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