Waves

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Across
  1. 4. waves spread through a gap
  2. 6. of waves per second
  3. 10. of wave that goes through a vacuum
  4. 11. waves change direction passing through different materials
  5. 12. is caused by these
  6. 13. of waves when they bounce off a surface
  7. 14. from midpoint to peak or trough of wave
  8. 15. between 2 identical points on wave
Down
  1. 1. energy
  2. 2. and vibrations are in same direction
  3. 3. used in medicine to see bones
  4. 5. are perpendicular to energy direction
  5. 7. too high for humans to hear
  6. 8. of wave that needs matter
  7. 9. of frequency
  8. 16. cannot travel through this
  9. 17. of Greek letter used for wavelength