17. What kind of wave require a medium to travel through?
A mechanical wave
B electromagnetic wave
C microwave
D. radio wave
16. TR is a substance or material through which a wave can propagate or produce A. structure
B medium
C object
D. body
19. What is the lowest point of a wave? A amplitude
B. trough
C. cres
D. wavelength
20. It is the height of a wave and also measures its intensity
A trough
B frequency
C. crest
D amplitude​