Matter, radiation and quantisation
Why is the energy of an atom quantised, and where does radiation come from?
16 lessons
Lessons
Quantisation and the atom
Chapter 1The photoelectric effect and the photonWhy does even weak ultraviolet light release electrons from a zinc plate, while bright red light does not release a single one?
- Chapter 2Spectra reveal the energy levels of atoms
Why do narrow dark lines cross the rainbow colours of sunlight, and how can they tell us which elements there are in the Sun?
- Chapter 3Energy levels of the hydrogen atom and the Bohr model
Why does the light of a lamp containing hydrogen split on a grating into just four clearly visible coloured lines, and why exactly at the wavelengths $656\,\text{nm}$, $486\,\text{nm}$, $434\,\text{nm}$ and $410\,\text{nm}$?
- Chapter 4Light and electrons as waves and particles
Why does very weak light or an electron beam draw first random single points on the screen, from which a fringe pattern arises only after thousands of hits?
- Chapter 5The wave-mechanical model of the atom and orbitals
Why is the electron of an atom drawn in a chemistry book as a fuzzy cloud and not as a small ball going round the nucleus along an orbit?
Quantum technology
Chapter 6Light from an LED and measuring the Planck constantWhy does a blue LED need a higher voltage than a red LED to light up?
- Chapter 7Lasers and quantum structures
Why does the light of a laser pointer cross a dark classroom as a narrow beam and show on the wall as a small dot, while the light of a torch spreads into a large, dim patch?
The nucleus and nuclear energy
Chapter 8The atomic nucleus and radioactive decayWhy does a small sample of americium in a smoke detector keep emitting particles, and what happens to an americium nucleus when a particle leaves?
- Chapter 9The decay law and half-life
Why does the activity of a hospital's technetium preparation always halve in about six hours, even though nobody can predict when a single nucleus will decay?
- Chapter 10Mass defect and nuclear binding energy
Why is a helium-4 atom lighter than two hydrogen atoms and two neutrons put together, even though it consists of exactly those particles?
- Chapter 11Fission, fusion and nuclear power
Why does one gram of uranium-235 release as much energy in fission as about $3.4$ tonnes of coal do when burned?
Radiation and people
Chapter 12Ionising radiation and the bodyWhy does a sheet of paper stop alpha radiation while gamma radiation passes through the whole human body, and why is a substance that emits alpha radiation nevertheless the most dangerous one when it gets inside the body?
- Chapter 13Radiation dose and radiation safety in Finland
Why do nuclear power plants give a Finn only a negligible part of their radiation dose, and where does the rest come from?
- Chapter 14Radiation in medicine and technology
Why is a patient injected with radioactive sugar in a PET scan, and how does the scanner work out where inside the body the radiation came from?
Particles and the universe
Chapter 15The Standard Model: elementary particles and interactionsWhy does a free neutron decay in about a quarter of an hour on average, while the decay of the proton has never been observed, even though both are made of the same particles?
- Chapter 16The evolution of the universe
Why have the spectral lines of distant galaxies shifted towards red, and the more so the farther away the galaxy is?
Apply independently
At the end of the module you can try whether you can apply what you have learned independently, in the style of the matriculation examination. The model answers and marking guides open after your own solution.
- Apply independently 5 tasks · 84 points
Module goals
Show all 3 goals
The student
- knows the effects of ionising radiation and becomes familiar with the safe use of radiation
- becomes familiar with the worldview based on quantum physics, from elementary particle physics to cosmology
- understands the importance of technology based on quantisation in modern society