11-15. Identify the following.
11. Is a disturbance that travels through a vacuum and carries energy. ¬¬¬________________
12. Is the number of waves it produces per unit time. _____________________
13. Is the distance between any two successive points in a wave that are in phase with each other. _____________
14. Is the time taken for one complete cycle of the wave to pass a reference. ________________
15. Is the distance travelled by the wave per unit time. ________________