CAIE A-Level Physics 22.3 Wave–Particle Duality

Practise using photoelectric, interference and electron-diffraction evidence for wave-particle duality and calculating de Broglie wavelength from momentum.

Exam points

use photoelectric, interference and diffraction observations as evidence for wave�particle duality
interpret electron-diffraction evidence for the wave nature of particles
calculate and interpret de Broglie wavelength from particle momentum

Covered syllabus points

22.3.1—The photoelectric effect provides evidence for a particulate nature of 22.3.2—And interpret qualitatively the evidence provided by electron diffraction 22.3.3—The de Broglie wavelength as the wavelength associated with a moving 22.3.4—Λ = h / p

[Maximum number: 6]

(a)

State an effect, one in each case, that provides evidence for

[ 2 ]

(i)

the wave nature of a particle,

[ 1 ]

(ii)

the particulate nature of electromagnetic radiation.

[ 1 ]

(b)

State what is meant by the de Broglie wavelength.

[ 2 ]

(c)

Calculate the speed of an electron having a de Broglie wavelength equal to the wavelength in (b)(ii).

speed =

$\mathrm{ms}^{-1}$

[ 2 ]

$\lambda=h / m v$

\begin{aligned} v & =\left(6.63 \times 10^{-34}\right) /\left(9.11 \times 10^{-31} \times 4.35 \times 10^{-7}\right) \\ & =1.67 \times 10^{3} \mathrm{~ms}^{-1} \end{aligned}

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Covered syllabus points

22.3 Wave–particle duality question 1

Question (a)

Question (i)

Question (ii)

Question (b)

Question (c)