![]() ![]() These determined the wavelengths of those emissions with amazing precision-so accurately, that at one time the standard of length, the "meter," was redefined in terms of the wavelength of a certain spectral feature. Spectrometers could be teamed up with sophisticated optical "interferometers" based on the wave nature of light (touched upon in an optional section at the end of the lesson plan for section S-4). Hydrogen glowed mainly in red, and sunlight contained a yellow line (close to the sodium twins, actually) ultimately ascribed to a new element " helium" (Helios is Sun in Greek). Thus sodium glowed in twin "lines" in orange-yellow, closely spaced (they are called "lines" because that is how they appear when observed in a spectrograph, which separates light coming from a narrow slit into wavelengths). In studying atoms, precise information seemed to be contained in the wavelengths of spectral lines, of sharply defined colors emitted by atoms in a glowing gas, each of which associated with a specific kind of atom. Where physicists confront the unknown and need to test various explanations, they look for evidence which can be observed with great precision, like the motions of planets, which provided a sensitive test of Newton's theories. the physics behind chemical bonding, by which atoms combined to form molecules. Phenomena associated with the atoms themselves, however, were not at all understood, e.g. All material objects seemed made up of particles too small to be seen, but whose existence could be deduced from a host of subtle phenomena. ![]() Technology closely followed this new physical understanding and made it pay handsomely, giving around the year 1900 electric motors, steam turbines, telegraphs and telephones, ice-making machinery, airships and more. Electricity obeyed the laws of Ampere, Faraday and Maxwell, and light was revealed to be an electromagnetic wave, an identification underscored by the discovery of radio waves by Heinrich Hertz, who generated them from a rapidly alternating electrical current. Motions obeyed Newton's Laws, which explained the motion of celestial objects with remarkable accuracy. etc.) was thought to be well understood (except, as Lord Kelvin supposedly remarked, for a few details.).
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |