# Physics Topic: Quantum Mechanics

Show an appreciation of the particulate nature of electromagnetic radiation.

Recall and use

*E = hf.*Show an understanding that the photoelectric effect provides evidence for a particulate nature of electromagnetic radiation while phenomena such as interference and diffraction provide evidence for a wave nature.

Recall the significance of the threshold frequency.

Recall and use the equation 1/2

*m*(*v*_{max})^{2}=*eV*, where_{s}*V*is the stopping potential._{s}Explain photoelectric phenomena in terms of photon energy and work function energy.

Explain why the maximum photoelectric energy is independent of intensity whereas the photoelectric current is proportional to intensity.

Recall, use and explain the significance of

*hf =**f**+ 1/2m*(*v*_{max})^{2}.Describe and interpret qualitatively the evidence provided by electron diffraction for the wave nature of particles.

Recall and use the relation for the de Broglie wavelength

*= h/p*.Show an understand of the existence of discrete electron energy levels in isolated atoms (e.g. atomic hydrogen) and deduce how this leads to spectral lines.

Distinguish between emission and absorption line spectra.

Recall and use the relation

*hf*=*E*_{1}*–**E*_{2}.

For H2 syllabus only:

Explain the origins of the features of a typical X-ray spectrum using quantum theory.

Show an understanding of and apply the Heisenberg position-momentum and time-energy uncertainty principles in new situations or to solve related problems.

Show an understanding that an electron can be described by a wave function

*ψ*where the square of the amplitude of the wave function l*ψ*l^{2}gives the probability of finding the electron at a point. (No mathematical treatment is required.)Show an understanding of the concept of a potential barrier and explain qualitatively the phenomenon of quantum tunnelling of an electron across such a barrier.

Describe the application of quantum tunnelling to the probing tip of a scanning tunnelling microscope(STM) and how this is used to obtain atomic-scale images of surfaces. (Details of the structure and operation of a scanning tunnelling microscope are not required.)

Apply the relationship transmission coefficient

*T*= exp(-2*kd*) for the STM in related situations or to solve problems. (Recall of the equation is not required.)Recall and use the relationship

*R*+*T*= 1, where*R*is the reflection coefficient and*T*is the transmission coefficient, in related situations or to solve problems.