Light

Light

How It Travels
1. Light travels in straight lines at a very high speed.
  1. Light is represented by rays, which are straight lines with an arrow to show the direction the light travels in.
When Light Hits Objects
1. Light comes from sources like the Sun, flames, light bulbs and hot objects. These objects are luminous.
2. Light reflects off some objects so we see them. These objects are non-luminous.
3. Light is absorbed by objects which appear black.
Reflection
1. Light reflects off a plane mirror so that the angle of incidence equals the angle of reflection. Angles are measured from the normal.
  1. The image in a flat mirror appears as far behind the mirror as the object is in front of it.
  2. The image in a flat mirror is the same way up as the object.
  3. The image in a flat mirror is the same size as the object.
How Light Travels Through Objects
1. Light is stopped by opaque substances which cast shadows.
2. Light goes through translucent substances but breaks up so you cannot see things clearly through them.
3. Light goes through transparent things so you can see things through them. When light goes through we say it is transmitted.
4. Light bends when it passes from one transparent substance to another. This is called refraction.
Spectrum
1. When light can be split into a spectrum by a prism. The colours are red, orange, yellow, green, blue, indigo and violet.
  1. Red filters let through red light and absorb the rest of the spectrum. Other colour filters work in a similar way.
  2. A red object reflects red light and absorbs other colours so it will look black in pure green light. A blue object will appear black in pure red light because it absorbs red light and reflects blue light.

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