Physics · Pearson Edexcel 9PH0 · Topic 5

Waves and the particle nature of light

Waves, superposition, refraction, lenses, polarisation, diffraction, and the particle nature of light and electrons.

  • 38 sub-topics
  • Taught in Year 12
  • 338 practice questions
  • 38 animated lessons
Practice questions (338) Lessons Worksheets All Edexcel Physics topics

What the specification says

Every sub-topic Pearson Edexcel can examine in this topic, with its reference number from the official specification. The Y12 and Y13 tags show when each sub-topic is usually taught.

  1. 59Amplitude, frequency, period, speed and wavelengthY12
  2. 60The wave equation, v = fλY12
  3. 61Longitudinal wavesY12
  4. 62Transverse wavesY12
  5. 63Graphs of wavesY12
  6. 64CP6: Determine the speed of sound in air using a 2-beam oscilloscopeY12
  7. 65Superposition, coherence, path difference and phaseY12
  8. 66Phase difference and path differenceY12
  9. 67Standing waves, nodes and antinodesY12
  10. 68Speed of a transverse wave on a stringY12
  11. 69CP7: Factors affecting the frequency of a vibrating stringY12
  12. 70Intensity, I = P/AY12
  13. 71Refraction, Snell's law and refractive indexY12
  14. 72Critical angleY12
  15. 73Total internal reflectionY12
  16. 74Measuring refractive indexY12
  17. 75Focal length of converging and diverging lensesY12
  18. 76Ray diagramsY12
  19. 77Power of a lens, P = 1/fY12
  20. 78Thin lenses in combinationY12
  21. 79Real and virtual imagesY12
  22. 80The thin lens equationY12
  23. 81MagnificationY12
  24. 82Plane polarisationY12
  25. 83Diffraction and Huygens' constructionY12
  26. 84Diffraction grating, nλ = d sin θY12
  27. 85CP8: Determine the wavelength of light using a diffraction gratingY12
  28. 86Electron diffractionY12
  29. 87De Broglie wavelengthY12
  30. 88Transmission and reflection at interfacesY12
  31. 89Pulse–echo techniqueY12
  32. 90Wave and photon models of electromagnetic radiationY12
  33. 91Photon energy, E = hfY12
  34. 92Photoelectric emissionY12
  35. 93Threshold frequency, work function and the photoelectric equationY12
  36. 94The electronvoltY12
  37. 95Photoelectric effect as evidence for the particle nature of lightY12
  38. 96Atomic line spectra and energy levelsY12

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Easy, medium and hard questions from this topic, each with a worked solutions and the mark for every step. All 338 questions in this topic, free, no account needed.

Waves and the particle nature of light

Easy

The wave equation · Year 12 · 2 marks

A tuning fork produces a sound of frequency 440 Hz. The wavelength of the sound in air is 0.78 m.
  1. Calculate the speed of sound in air.
    (2)

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  1. Wave speed = frequency × wavelength.v=fλ=440×0.78v = f\lambda = 440 \times 0.78
  2. Round to match the data.v=343 m s−1v = 343\ \mathrm{m\,s^{-1}}

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Waves and the particle nature of light

Medium

The photoelectric effect · Year 12 · 4 marks

Light of wavelength 400 nm falls on a metal surface with work function 2.3 eV.
  1. Calculate the maximum kinetic energy of the emitted electrons, in eV.
    (4)
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  1. Find the energy of one photon. Convert nm to m first.EE=hcλ{}= \dfrac{hc}{\lambda}=6.63×10−34×3.00×1084.00×10−7{}= \dfrac{6.63 \times 10^{-34} \times 3.00 \times 10^{8}}{4.00 \times 10^{-7}}=4.97×10−19 J{}= 4.97 \times 10^{-19}\ \mathrm{J}
  2. Convert the work function to joules so the units match.ϕ\phi=2.3×1.60×10−19{}= 2.3 \times 1.60 \times 10^{-19}=3.68×10−19 J{}= 3.68 \times 10^{-19}\ \mathrm{J}
  3. hf=ϕ+Ek(max⁡)hf = \phi + E_{k(\max)}: the photon's energy pays the work function and the rest becomes kinetic energy.Ek(max⁡)E_{k(\max)}=4.97×10−19{}= 4.97 \times 10^{-19}−3.68×10−19{}- 3.68 \times 10^{-19}=1.29×10−19 J{}= 1.29 \times 10^{-19}\ \mathrm{J}
  4. Divide by 1.60×10−191.60 \times 10^{-19} to convert back to electronvolts.=0.81 eV= 0.81\ \mathrm{eV}

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Waves and the particle nature of light

Hard

Refraction and total internal reflection · Year 12 · 9 marks

Figure 1 shows a ray of light passing from air into a transparent block of refractive index 1.52. The angle of incidence is 35°.
35°rairblock
Figure 1
  1. (a)
    Calculate the angle of refraction.
    (3)
  2. (b)
    Calculate the speed of light in the block.
    (2)
  3. (c)
    Calculate the critical angle for the boundary between the block and air.
    (2)
  4. (d)
    State the two conditions needed for total internal reflection at a boundary.
    (2)

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Part (a)3 marks

  1. Snell's law, with n=1n = 1 for air.n1sin⁡θ1=n2sin⁡θ2n_1\sin\theta_1 = n_2\sin\theta_2
  2. Rearrange for sin r.sin⁡r\sin r=sin⁡35∘1.52{}= \frac{\sin 35^\circ}{1.52}
  3. r=22.2 ∘r = 22.2\ \mathrm{^\circ}

Part (b)2 marks

  1. Refractive index is the ratio of the speeds.vv=cn{}= \frac{c}{n}=3.00×1081.52{}= \frac{3.00 \times 10^8}{1.52}
  2. vv=1.97×108 m s−1{}= 1.97 \times 10^{8}\ \mathrm{m\,s^{-1}}

Part (c)2 marks

  1. At the critical angle the angle of refraction is 90°.sin⁡θc=11.52\sin\theta_c = \frac{1}{1.52}
  2. θc=41.1 ∘\theta_c = 41.1\ \mathrm{^\circ}

Part (d)2 marks

  1. Dense to less dense.The light must be travelling from the material with the higher refractive index towards the one with the lower.
  2. Beyond the critical angle there is no refracted ray.The angle of incidence must be greater than the critical angle.

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