Available Answers

1. 1.

   Fill in the blanks.

   1. ___________ is a type of energy that helps us to see objects around us.
   2. Objects that emit light are called ___________.
   3. The speed of light is ___________.
   4. The objects or materials through which light can pass are called ___________.
   5. Light travels in a ___________ line.
   6. When light strikes the ___________, it is blocked.
   7. A shadow where there is complete darkness is called ___________.
   8. Another region that is outside the umbra that is partially dark is called ___________.
   9. ___________ is a simple device of the property of rectilinear propagation of light.
   10. ___________ is a clock that uses the position of the sun to indicate the time.
2. 2.

   Tick (√) the correct answer:

   1. Light travels fastest through
      1. glass
      2. air
      3. water
      4. none of these
   2. Objects that do not allow any light to pass through them are called
      1. transparent objects
      2. translucent objects
      3. opaque objects
      4. none of these
   3. The shape of a shadow depends on
      1. the position of the source of light
      2. the size of the source of light
      3. the shape of the object
      4. all of the above
   4. The colour of a shadow is
      1. always black
      2. always white
      3. same as that of the object
      4. none of these
3. 3.

   Fill in the following blanks:

   1. An object that does not allow light to pass through it at all, is called __________________.
   2. An object that partially allows light to pass through it is called __________________.
   3. The partially dark part of the shadow of an object is called __________________.
   4. The colour of the shadow is always __________________.
   5. __________________ reflect the entire amount of light that falls on them.
4. 4.

   Write 'T' for true and 'F' for false:

   1. The umbra is a region of total darkness.
   2. The penumbra is a region of partial darkness.
   3. An eraser is a transparent object.
   4. The sun and the stars are natural sources of light.
   5. Light travels in a straight line.
   6. Jugnu does not emit light of its own.
5. 5.

   What is light?