Chapters 3 and 4 crossword

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Across
  1. 4. the ratio of output work to input work
  2. 5. sum potential and kinetic energy system
  3. 6. allows almost all light to pass through
  4. 10. a layer of light-sensitive cells back of eye
  5. 11. force moves an object in the direction of the force
  6. 12. controls how much light enters the eye
  7. 13. the energy stored in bonds between atoms
  8. 15. a reflected sound wave
  9. 17. allows some light to pass through
  10. 19. a convex lens on the outside of the eye
Down
  1. 1. the energy in motion
  2. 2. the energy carried by electromagnetic waves
  3. 3. the energy stored in the nucleus of an atom
  4. 4. the energy carried by an electric current
  5. 7. opening at the center of the iris
  6. 8. energy transferred through the ground
  7. 9. stored energy
  8. 14. the perception of how high or low a sound seems
  9. 16. does not allow light to pass through
  10. 18. sum kinetic potential energy particles