Answer:Reflection
Explanation:
The throwing back of a sound wave without absorbing it is called reflection
In acoustic reflection of sound is termed as echo i.e. sound arrived at the listener after a particular delay depending upon the position of barrier to the observer.
The reflection of sound is used in many devices like megaphone, trumpets, etc. It is also used in auditorium such that the ceiling of the auditorium is curved for multiple reflections of sound so that sound can be reached at every corner of the auditorium.
It involves electrons.
The cathode is the electrode where electron deficient ions move to.
While the anode is electrode where electron excess ions move to.
So the relationship between Cathode and Anode involves electrons.
C.
pitch goes up on approach ... Doppler effect
