On Fri, 22 Oct 2004, No Religion wrote: > Hi, > I'd like to understand more intuitively the subject. > > First of all, I've the following questions to ask, if you don't mind: > > 1) A transformer and a system composed by a radio transmitter and a > radio receiver use the same underlying physical phenomena? Yes except the transformer transmits mostly the magnetic field and the radio link mostly the electrical. In free space (air, vacuum, most insulators) the electromagnetic field energy is roughly equally divided between megnetic and electric fields. In special materials like magnetic cores (and others), one of the components is predominant. > 2) Does magnetism really exist in itself, or is it just electricity > that manifests itself into a particular way? What is it (this way)? Magnetism is not. There is no physical property called 'magnetism'. There is magnetisation, magnetic field strength and such. Static magnetic fields are associated with a quantic phenomenon known as 'spin'. The spin is an analog of dc current in a certain way. > 3) If an electrical static field starts changing (e.g. sinusoidally), > i.e. it stops being static, is it enough to call it an electromagnetic > field? Yes. Every material has a characteristic propensity to store electrical and magnetical energy. These two types of energy are coupled, and disturbance propagate with the speed of light (in that material), and when you change one the other changes too. So you can 'start' an em. field by changing the current in a coil or by applying a batter to a wire. It does not have to be sine. *change' is enough. The equaltions that describe this coupling between electrical and magnetic fields in matter are known as Maxwell equations. Peter _______________________________________________ http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist