Foraged Facts
a. Undersea rocks solidify quickly to retain their magnetism and record earth's magnetic history. The records show 14 magnetic pole reversals in the last 5 million years. but nobody knows why the magnetic poles flip around like that; or what makes the earth a magnet in the first place. It is thought that the pole reversals imply that the magnet weakens and goes through a "zero point" in between reversals and that we just passed such a condition (1997).If true it could explain why so many migratory birds, have been getting lost lately.)
b. The full name of the U.K. is: "The United Kingdom of Great Britain, Northern Ireland and Berwick-upon-Tweed." The reason for this being that Berwick-upon-Tweed has historically been a disputed border town between England and Scotland
What is fire ?
Fire involves a chemical reaction between fuel and atmospheric oxygen. Once initiated it is self-sustaining, enerates high temperatures and releases a combination of heat, light, noxious gases and particulate matter. The visible flame is the region in which this chemical process occurs and so flame is essentially a gas phase phenomenon. For flaming combustion to occur, solid and liquid fuels must be converted into gaseous form. For liquid fuels this is achieved by evaporative boiling. For solid fuels, the solid is chemically decomposed through the process of pyrolysis to generate volatile gases. a. A flame is a region containing very hot atoms. At high enough temperatures all atoms will emit energy in the form of light as their electrons, which have been prompted to higher energy levels by absorbing heat energy, fall to lower energy states. Because this light is emitted in discrete quanta according to the relationship E = hv (where E = energy, h = Planck's constant and v = frequency), flame colour is related to the magnitude of the energy quantum which is transformed to light. This can most easily be seen with a Bunsen burner. A Bunsen burner that has a choked air supply burns cool, the light emissions from carbon atoms are relatively low in energy and appear more red or orange. However, when the Bunsen is allowed air so that combustion is complete, the flame is hotter and the light emitted is of a higher energy and frequency and appears blue.The luminescence of a flame is only half of the story. The structure of the flame region is important to understand too. The flame area in a normal combustion environment, such as an open-air bonfire, is structured by convection currents which form as hotter, lighter air rises and allows cooler fresh air to replace it. It is this channelling effect and movement of air that shapes the dancing flames. It is interesting that in space, in zero gravity, the hotter and cooler air cannot move by convection, so flames take on weird shapes and may be stifled by their own combustion products.
Why can you see through water?
For an answer the question should be turned around. What matters is what stops light in opaque mediums. Light is electromagnetic radiation existing as packets of energy called photons which act like waves and whose energy is precisely related to wavelength. Matter, consists of particles (atoms and molecules) which include electrons. Electrons only exist at certain energy states and a photon which makes contact with a particle may excite an electron or molecule to a higher energy state. This can only occur if the energy of the photon is exactly the same as the energy required to raise the electron from one energy state to another. If this occurs, photons of this particular wavelength are absorbed and the matter is opaque to the light radiation. Some substances are translucent. Photons can pass through matter if they have wavelengths which are not absorbed and many materials allow photons to pass, but some deflect the photons in many directions (scattering). Such substances behave as they do because waves can interact with objects which have a similar size to their wavelength. This is known as interference. Crystals are good examples of translucent substances because they are regular arrays of atoms, and the distances between their atoms can be similar to the wavelengths of the photons. So photons which pass through crystals can be deflected (refraction) and are scattered. A material is transparent if it transmits photons which continue in their original direction, or are all deflected by the same change in direction. Such transmitted radiation retains any image which it had when it entered the material. Transparent materials contain very little crystalline material and their atoms and molecules are arranged in an irregular pattern making them glassy or amorphous. This induces negligible scattering because the net effect of any scattering that is induced is zero. Materials may be transparent to some wavelengths of light but not others. Visible light has a limited range of wavelengths. Even so, different wavelengths are seen as different colours. Some materials may be transparent to some colours but opaque to others which explains, for example, tinted spectacles.
Why is the static of a colour TV black & white?
When enough of a TV signal is received to give a reasonable picture, there is, hidden within the information, a "colour burst" which tells the receiver that a colour signal is being transmitted. This is usually omitted when old monochrome films are shown so that the black and white and shades of grey are reproduced as clearly as possible. The colour burst locks an oscillator in the receiver so that the colour signal, in the form of phase modulation, can be decoded. When a receiver is operated without an incoming signal, the input circuits are working at maximum gain (seeking to find what is not there). So what we see is a combination of the noise of the cosmos plus the noise in the input stages of the receiver. But what is important is that there is no colour burst, the oscillator is not locked and so the spots are monochrome.
Do bumblebees defy physics ? The infamous case of the flightless bumblebee is a classic example of carelessness with approximations. It stems from someone trying to apply a basic equation from aeronautics to the flight of the bee. The equation relates the thrust required for an object to fly to its mass and the surface area of its wings. In the case of the bee, this gives an extremely high value--a rate of work impossible for such a small animal. So the equation apparently "proves" bees cannot fly. However, the equation assumes stationary rather than flapping wings, making its use in this case misleading. Of course if equations fail in physics there is always empirical observation--if a bee looks as if it is flying, it most probably is.
