PHYSICS CONNECTION
Momentum determines a particle’s wavelength
A particle’s de Broglie wavelength decreases as its momentum increases. The same momentum quantity used in mechanics appears in wave–particle duality.
λ = h/p For non-relativistic particles: p = mv
Follow the reasoning
- Calculate momentum from the particle’s mass and speed.
- Divide Planck’s constant by the momentum.
- Compare the wavelength with the relevant experimental scale.
OFFICIAL OCR QUESTIONS
Try it in a past paper 1
Open the question, then use its mark scheme to check your work.
Question 8
Describe electron diffraction and compare the de Broglie wavelengths of electrons and a car.
A curated collection checked against the question papers and mark schemes; not a complete past-paper catalogue. Links open official OCR PDFs in a new tab.
ORIGINAL PHYSICSUK QUESTIONS
Put the ideas to work
More practice is on its way
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Specification outcomes (3)
- 3.5.1(b) Define linear momentum, p = mv, and understand its vector nature.
- 4.5.3(a) Describe and explain electron diffraction as evidence of wave-like behaviour of particles.
- 4.5.3(c) Use the de Broglie equation λ = h / p to relate momentum and wavelength.