Light and sound

123456789
Across
  1. 1. can be seen
  2. 2. can be heard
  3. 3. maximum position of wave
  4. 8. do not require a medium for them to move.
  5. 9. hertz
Down
  1. 1. cause the medium to move parallel to the direction of the wave.
  2. 4. a material that moves energy or light from one substance to another
  3. 5. space in which there is no matter
  4. 6. cause the medium to move perpendicular to the direction of the wave.
  5. 7. require a medium to propagate.