12. Dual character of light - proofs of both wave and corpuscular nature of light. (4p.) Flashcards
Dual character of light
Waves can be described as particles; particles, as waves. Diffraction and interference phenomena reveal a wavelike character of light, but the photoelectric effect shows light to have a particle-like character as well. Electrons have mass but can be diffracted like waves. All particles turn out to have a wavelike character described by de Broglie wavelengths.
The concepts of wave and particle are so different that it is hard to understand how light can be both. But in fact, both aspects are complementary. Light is at the same time a wave and a stream of particles, called photons.
Corpuscular nature of light:
There are a few experiments, which support the thesis that light has a corpuscular nature, amongst which are: Bremsstrahlung (promieniowanie hamowania, jak chcecie sobie poczytać o tym, to śmiało ja nie zamierzam xd), Bothe (proved the existence of discrete photons, didn’t support the wave part of the experiment), Compton effect (the scattered radiation experiences a wavelength shift that cannot be explained in terms of classical wave theory).
Generalnie powiedział, że wystarczy jeden opisać bardziej, więc jeżeli wymienimy kilka i opiszemy photoelectric, to jesteśmy w domu.
Photoelectric effect – light delivers wave energy; electrons transform it into particle energy. The energy delivered by the light cannot be explained in terms of the wave model, as it depends on the frequency of the light, not its intensity. It is carried in discrete bundles called photons.
Wave nature of light:
Diffraction/interference – in interactions with itself, light energy is spread continuously across space in the form of waves.
Young’s double slit experiment (przy pisaniu słowa dyfrakcja od razu można dać ten eksperyment) – when the light is shone through a double slit, it is diffracted, overlaps and gives a diffraction pattern on the screen.
