crossword puzzle by:Vincent Ruegger

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Across
  1. 4. to give off light (from a light source)
  2. 5. the natural agent that stimulates sight and makes things visible.
  3. 6. position
  4. 8. the appearance of objects to the eye with respect to their relative distance
  5. 10. to use a code to convert letters into symbols
Down
  1. 1. when light shines on an object
  2. 2. to send out a signal (by radio waves)
  3. 3. a model of light that represents the direction of light
  4. 7. to use a code to convert symbols into letters (words)
  5. 9. a system of signals or symbols used to communication