Electromagnetism and light
How are electricity and magnetism linked, and what is light?
16 lessons
Lessons
Magnetic field and magnetic force
Chapter 1Magnets, the magnetic dipole and the magnetic fieldWhy does a compass needle in the forest always point north, but swing away the moment a magnet is brought next to it?
- Chapter 2Charged particle in electric and magnetic fields
Why can a laboratory tell the carbon-14 atoms of an ancient piece of wood from ordinary carbon atoms, although they behave the same chemically and there is only about one in a trillion of them?
- Chapter 3Magnetic field of a wire and a coil
Why can the magnet of a scrapyard crane lift a tonne of scrap car into the air and drop it at the press of a button, when a fridge magnet never lets go?
- Chapter 4Force on a current-carrying wire: the electric motor and the loudspeaker
Why does a loudspeaker cone vibrate and the blades of a desk fan turn, when nothing visible pushes either of them?
Induction and electrical energy
Chapter 5Electromagnetic inductionWhy does a bicycle dynamo light the lamp only while the wheel is turning, even though the dynamo contains no battery or accumulator?
- Chapter 6Lenz's law and eddy currents
Why does a strong magnet take several seconds to fall through a copper tube, although copper is not magnetic and an ordinary object falls the same distance in less than a second?
- Chapter 7The generator and alternating current
Why does the rotating rotor of a wind turbine produce in the electricity grid a voltage that reverses its direction a hundred times a second?
- Chapter 8The transformer and the transmission of electrical energy
Why is electricity carried from a power plant to a city at a voltage of $400\,\text{kV}$, when the voltage at a socket at home is only $230\,\text{V}$?
Radiation and the propagation of light
Chapter 9Electromagnetic radiation and the black-body spectrumWhy does an iron bar heated in a forge glow first red and then more and more yellow, and why can a thermal camera see a person even in pitch darkness?
- Chapter 10Reflection and refraction of light
Why does a straw in a glass of water seem to break exactly at the surface of the water?
- Chapter 11Dispersion: the prism and the rainbow
Why is the red of a rainbow always on the outer edge and the violet on the inner edge, and why can you see a rainbow only when the sun is behind you?
- Chapter 12Total internal reflection and optical fibre
Why can light travel in a glass fibre along the bed of the Baltic Sea from Helsinki to Germany without escaping on the way, even though glass is transparent?
Wave phenomena of light
Chapter 13Interference and diffraction of lightWhy does the beam of a laser pointer draw a whole row of dots of light on the wall when it passes through a thin transparent film?
- Chapter 14Thin-film interference
Why do bright bands of colour appear on the surface of a soap bubble, even though soapy water is colourless?
- Chapter 15Polarisation of light
Why do polarised sunglasses remove the glare reflected from the surface of a lake, when ordinary sunglasses that are just as dark only dim everything?
- Chapter 16Applied chapter: wireless charging, the induction hob and the fibre link
Why does a phone charge without a cable, a pan get hot without a flame and an internet connection travel as light in a glass fibre?
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 · 83 points
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Module goals
Show all 4 goals
The student
- understands the central importance of induction in electromagnetism
- understands the physical basis of producing and transmitting electrical energy and its importance for society
- recognises sources and effects of electromagnetic radiation
- understands light as an electromagnetic phenomenon