Physics crossword

4. 9 across vary in magnitude or position in a regular manner around a central point
5. 10 down the change in direction of a wave passing from one medium to another caused by its change in speed
8. 13 down the apparent difference between the frequency at which sound or light waves leave a source and that at which they reach an observer
10. 9 across the level of volume we can hear
13. 4 down can be thought of as a disturbance or oscillation that travels through space-time, accompanied by a transfer of energy
14. 10 across the distance traveled by a given point on the wave (such as a crest) in a given interval of time
16. 17 across are waves in which the vibration of the medium is parallel ("along") to the direction the wave travels
18. 5 across this is the form a wave length makes
19. 5 down technique for detecting and determining the distance and direction of underwater objects by acoustic means

1. 12 across property of certain electromagnetic radiations in which the direction and magnitude of the vibrating electric field are related in a specified way
2. 6 down the time that it takes to do something
3. 15 down motion in which all points on a wave oscillate along paths at right angles to the direction of the wave's advance.
6. 9 the maximum amount of displacement of a particle on the medium from its rest position
7. 20 down are waves that are created as a result of vibrations between an electric field and a magnetic field
9. 15 across a wave that is not capable of transmitting its energy through a vacuum
11. 9 occurs widely in nature, and is exploited in many devices
12. 12 across the net effect of the combination of two or more wave trains moving on intersecting or coincident paths
13. 10 down this is what we have been learning
15. 11 down the spreading of waves around obstacles
17. 6 this is the bottom of the crest