Friday, 19 December 2008
Kilometers to Nanometers
Charges in an AC electrical circuit vibrate at a frequency of 50 -60 Hz. AC electricity works on the basic theory of a generator pumping charges in the cable to create a flow of electrical energy, or rather, electromagnetic energy. Therefore the vibration of these charges at 50 - 60 times a second, emanates a wavelength of electromagnetic radiation we know as electricity. The size of this wavelength is 6000 km on a 50Hz supply, and it revolves around the cable. Electricity follows a cable route from the power station to your home and ends up in a light bulb. When we pass 50Hz electrical current through the substance (tungsten) of the lamp, it converts the energy into a very high frequency vibration - namely the visible light spectrum. In the visible light spectrum the charges are now vibrating at a frequency between 400 - 790 terahertz (THz). One terahertz is one trillion cycles per second. The wavelength of the electromagnetic energy has now been reduced from 6000 km to the region of 380 - 750 nanometers - the wavelength of visible light. A nanometer is equal to one billionth of a meter.
The electromagnetic radiation then travels from the lamp to the surface it is illuminating. This increases the velocity of the radiation. A higher velocity means a lower frequency, so the light now travels as infrared radiation until it reaches a surface. It is thought that 90% of the input energy of a light bulb is wasted as heat. Perhaps this is not the case at all. Maybe the light that is emitted by a lamp is simply travelling in the guise of heat. The frequency at which matter vibrates will dictate how it reacts with the electromagnetic waves, before the waves are reflected into the eye. My feeling is that the waves are thus converted into visible light in the eye, rather than at the object itself.
When we switch on the lamp it draws more power from the circuit and so the current increases. Current is a rate quantity - as is velocity a rate quantity. On a simple circuit, the current is everywhere the same. The current, even though under-going velocity, remains balanced throughout the circuit. This suggests another force at work, other than simply charge flowing from a higher potential to a lower potential. This balance of current could be created by a force working in the opposite direction - flowing from the lower potential to the higher potential. The current coming in is equal to the current going out. It's a point worth making here, but the neutral wire which carries current from the home, and back to the power station - carries a current but has no electric charge. In my mind, electromagnetic energy arises in the shape of a double helix which flows in both directions.
In Britain, the mains frequency is transmitted from the power plant to the household at 50 Hz. This frequency does not change throughout its transmission, so therefore the wavelengths of electricity remain the same. The higher the load, the higher the current - so therefore the velocity of the electromagnetic force must be increasing. Electric fields come from charges. So do magnetic fields, but from moving charges, or currents, which are simply a whole bunch of moving charges. In an electrical cable the charges are wiggling. They are not increasing their velocity as the current increases. They remain wiggling at a steady pace of 50 cycles per second. The electric field is proportional to the electric charge of an object, but does not depend on its velocity. The magnetic field depends on the charge and the velocity. Therefore, the velocity of an electric current would appear to be implied by the magnetic force.
What, if any, restrictions can be placed on the velocity of the magnetic field? It is supposed that each joule of EM energy flows at nearly the speed of light between generator and distant load. But what's stopping the magnetic field from moving faster than the speed of light?