Light and shadow: Light Strikes in Materials

When light strikes an object, it is transmitted or absorbed, reflected, or bent.

A material that allows mush light to pass through is called a transparent material.


Transparent materials are:


Clear glass, clear water, clear plastic



A material that allows small amount of light to pass through is called a translucent material.  The light is scattered in different directions so the object behind a translucent material cannot be seen clearly.


Translucent materials are:


Onionskin, some light bulb, frosted glass



A material that block most of the light that strikes them are called opaque material.


Opaque materials are:


Block of wood, cardboard, book, etc.




About Shadow

Shadows are formed when opaque materials block the path of light.


The shape and size of  shadow depends upon the distance and positions of the object from the source of light.



Two parts of a shadow


  1. Umbra is the darker part of the shadow.
  2. Penumbra is the lighter part of the shadow.


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