![]() Such a light stream is said to be coherent. Those photons could go on to hit other excited atoms, and soon you would have a stream of in-phase photons. The exciting part is that you would have two photons with the same energy and they would be in phase. He suggested that the atom would emit a photon with that amount of energy, and it would be accompanied by the original photon. He considered an atom excited by a certain amount of energy and what would happen if that atom were hit by a photon with the same amount of energy. In 1917, Albert Einstein was thinking about photons and excited atoms. There will always be some blurring of images, no matter what the size of the aperture or the wavelength of light used to make an image. Cloth and feathers, which are both made up of many smaller, thinner parts, produce complicated diffraction patterns.Perfect resolution is impossible. Light that passes around the hair spreads out, overlaps, and produces a diffraction pattern. Thin objects, such as a strand of hair, also diffract light. In fact, the angle between two adjacent dark bands in the diffraction pattern is inversely proportional to the width of the slit. The narrower the slit, the more the light spreads out. This different amount of bending gives the blobs their colored edges: blue on the inside, red on the outside. ![]() Red light, for instance, has a longer wavelength than blue light, so it bends more than blue light does. The angle at which the light bends is proportional to the wavelength of the light. Where the trough of one wave overlaps with the crest of another wave, the waves cancel each other out, and you see a dark band. Where the crest of one wave overlaps with the crest of another wave, the two waves combine to make a bigger wave, and you see a bright blob of light. The light waves that go through the slit spread out, overlap, and add together, producing the diffraction pattern you see. The black bands between the blobs of light show that a wave is associated with the light. Rotate each object while you look through it. Look at the light through a piece of cloth, a feather, a diffraction grating, or a piece of metal screen. Rotate the hair and watch the line of blobs rotate. Move the hair until it is between your eye and the light source, and notice that the light is spread into a line of blobs by the hair, just as it was by the slit. ![]() Stretch a hair tight and hold it about 1 inch (2.5 cm) from your eye. Notice that the blobs have blue and red edges and that the blue edges are closer to the light source. As you squeeze the slit together, the blobs of light grow larger and spread apart, moving away from the central light source and becoming easier to see. If you look closely you may see that the line is composed of tiny blobs of light. While looking through the slit, rotate the pencils until they are horizontal, and notice that the line of light becomes vertical. Notice that there is a line of light perpendicular to the slit. Squeeze the pencils together, making the slit smaller. ![]() Hold both pencils close to one eye (about 1 inch away) and look at the light source through the slit between the pencils. The tape wrapped around one pencil should keep the pencils slightly apart, forming a thin slit between them, just below the tape. ![]() Hold up the two pencils, side by side, with the erasers at the top. Place the light on a stable surface at least one arm’s length away from you. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |