Physics 9702 · AS & A Level · Wave-particle duality
Wave-particle duality — practice question
Electrons moving at speed $v$ in a vacuum strike a very thin carbon film, as shown in Fig. 7.1. The electrons that emerge then fall on a fluorescent screen, where a set of concentric rings is seen.
(a)[2]
Suggest why the rings that are observed provide evidence for the wave nature of particles.
(b)[3]
The initial speed of the electrons is increased. State and explain the effect, if any, on the radii of the rings seen on the screen.
(c)[4]
A proton and an electron are both accelerated from rest through the same potential difference. Determine the ratio
$\dfrac{\text{de Broglie wavelength of the proton}}{\text{de Broglie wavelength of the electron}}$.
Worked solution & mark scheme
This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Diffraction takes place through a suitable film / cork dust” …