Electromagnetic Puzzle

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Across
  1. 1. arrows go in
  2. 3. number of wave cycles in one second
  3. 5. positive charge
  4. 6. highest point
  5. 8. is invisible
  6. 9. lowest point
  7. 10. crest to crest
Down
  1. 2. speed of light
  2. 4. arrows go out
  3. 7. charge must be moving