Wave-particle duality

Which of the following provides evidence for the particle nature of electromagnetic radiation?

In an electron diffraction experiment, electrons are accelerated by a potential difference between a hot filament and an anode. The electron beam produced strikes a sample of crystalline material causing a diffraction pattern.

Which of the following would cause the angle of diffraction to increase?

Study of the photoelectric effect leads to observations that cannot be explained by the wave theory of light.

When ultraviolet light is shone on a charged zinc plate, electrons are released. When visible light is shone on the zinc plate, electrons are not released.

State what is meant by threshold frequency.

Explain why the observation of a threshold frequency is not consistent with the wave theory of light.

The photoelectric effect can be explained using the idea of photons.

State what is meant by the term photon.

The photoelectric effect provides evidence for the particle nature of electromagnetic radiation.

Which of the following observations of the photoelectric effect could also be explained using the wave nature of electromagnetic radiation?

Our understanding of the atom has developed over time, from early models in which atoms were considered to be hard incompressible spheres, through to the nuclear model of the atom and the ladder model in which electrons exist in a discrete number of allowed energy states.

*(a) The model of atoms as hard incompressible spheres, moving rapidly and randomly, can be used to explain why gases exert a pressure.

Explain, using ideas of momentum, why the pressure exerted by a gas increases as the temperature of the gas increases.

The nuclear model of the atom was established following a series of experiments in which alpha particles were directed at thin gold foil.

An alpha particle approaching a gold nucleus,¹⁹⁷₇₉Au, head-on will be brought to rest and returned along its original path.

Calculate the minimum distance between the alpha particle and the nucleus for alpha particles of energy of 5.5 MeV.

It is observed that electrons, with energy of 5.5 keV, are diffracted as they pass through the thin gold foil.

Explain a conclusion about the electrons that can be made from this observation.

In the energy ladder model of the atom, electrons exist in a discrete number of allowed energy states. The collision of electrons with gold atoms may lead to the production of high frequency electromagnetic radiation.

Explain how high frequency electromagnetic radiation may be produced when electrons collide with atoms in a metal.

In the 19th century experiments with magnetic and electric field deflections were used to determine the charge to mass ratio of electrons. Later experiments showed the diffraction of electrons as they passed through thin metal foils. Deduce what these experiments tell us about electrons.