Physics 9702 · AS & A Level · Wave-particle duality

Wave-particle duality — practice question

(a(i))[2]

Describe what wave-particle duality means.

(a(ii))[2]

State the relationship between a particle’s de Broglie wavelength $\lambda$ and its momentum $p$. State the meaning of any other symbols that you use.

(b)

A narrow beam of electrons, all travelling at the same speed, is incident normally on a carbon film. The electrons then continue to a fluorescent screen, as shown in Fig. 9.1. The apparatus is in a vacuum. The pattern formed on the screen is shown in Fig. 9.2.

(b(i))[2]

Explain why the pattern in Fig. 9.2 gives experimental evidence to show that the electrons have a wave nature.

(b(ii))[2]

The speed of the electrons is increased. Suggest, with a reason, how this change alters the pattern seen on the screen.

(i)[2]

Explain why the pattern in Fig. 9.2 gives experimental evidence to show that the electrons have a wave nature.

(ii)[2]

The speed of the electrons is increased. Suggest, with a reason, how this change alters the pattern seen on the screen.

Worked solution & mark scheme

This 12-mark question has a full step-by-step worked solution and mark scheme. One marking point: an electromagnetic wave may act as a particle

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