Light waves
Particle theory of light is that it acts like particles. Little light bullets that stream from the source. This explains how shadows work.
Wave theory of light is that light also acts like wakes, ripples in space, instead of bullets. This explains how rainbows work.
Spectral lines demonstrate that every element has a particular frequency associated with it. When a photon (a light particle) hits the elements atom, the light is absorbed. This creates dark bands in the spectrum at those frequencies. From colours you can tell the chemical compositions of the stars.
When light passes through a prism. it separates into the colours that make it up. White light changes to a swath of colours.
Scientist build special instruments to separate light, usually with gratings. These instruments are called spectrograph's.
Visible light is the only type of electromagnetic wave that is visible to the human eye. Visible light produce different colours depending on their wave length. An example of this is a red colour will appear if the light wave is long and violet wave will appear if the wave is short.
Wave theory of light is that light also acts like wakes, ripples in space, instead of bullets. This explains how rainbows work.
Spectral lines demonstrate that every element has a particular frequency associated with it. When a photon (a light particle) hits the elements atom, the light is absorbed. This creates dark bands in the spectrum at those frequencies. From colours you can tell the chemical compositions of the stars.
When light passes through a prism. it separates into the colours that make it up. White light changes to a swath of colours.
Scientist build special instruments to separate light, usually with gratings. These instruments are called spectrograph's.
Visible light is the only type of electromagnetic wave that is visible to the human eye. Visible light produce different colours depending on their wave length. An example of this is a red colour will appear if the light wave is long and violet wave will appear if the wave is short.
Telescopes- Reflecting Telescope
The primary mirror is located at the lower end of the telescope tube in a reflector and has its front surface coated with an extremely thin film of metal, such as aluminium. The back of the mirror is usually made of glass. Pyrex was the principal glass of choice for many of the older large telescopes, but new technology has led to the development and widespread use of a number of glasses with very low coefficients of expansion. A low coefficient of expansion means that the shape of the mirror will not change significantly as the temperature of the telescope changes during the night. Reflecting telescopes have a number of other advantages over refractors. They are not subject to chromatic aberration because reflected light does not disperse according to wavelength.
Refracting Telescope
A refracting telescope works just like a magnifying glass. It uses a convex glass lens (to bend light and bring it into focus. This lens is thicker in the center than it is toward its edges, which bends the light more at the edge of the lens than light coming through the center. This allows all of the light to come together at a focus point. The point of focus is where the image is created.