Physics Textbook/Summary

  • Light is a form of energy. It travels in straight lines.
  • The speed of light is constant in a vacuum. It is approximately equal to 3.0 x 108m/s.
  • Light rays are regularly reflected by smooth, shiny surfaces. Images form on these surfaces. These are irregularly reflected by rough surfaces. No image forms on these surfaces.
  • Light rays are refracted when they pass at an angle from one medium to another.
  • Light travels in a less dense than in a denser medium.
  • Sunlight separates into different colors, called the visible spectrum, as it passes through a prism. The spectrum consists of the colors of the rainbow: red, orange, yellow, green, blue, indigo, and violet.
  • Dispersion is the separation of visible light into its different colors: red, orange, yellow, green, blue, indigo, and violet.
  • Red, green, and blue (RGB) are the primary colors in light.
  • When white light falls on an object which does not transmit light, one of the following happens:
    • all of the colors in white light are reflected: the object will appear light;
    • some of the colors may be reflected: the object appears colored; and
    • all the colors are absorbed by the object: the object appears black.
  • The colors of opaque objects are the colors they reflect and which reaches our eyes. The colors of transparent materials are the colors they transmit.
Last modified on 19 January 2013, at 18:24