As a train approaches the sound waves are crowded together (compressed) and produce a higher pitch. As the train moves away the sound waves move farther apart (elongate) and produce a lower pitch. What term is used to describe this effect?

b.transmitters send radio waves, and receivers capture radio waves.

the working equation for the angular size is the product of the physical size and 360 degrees divided by the product of two pi and distance from earth. the minimum size would be 0.559 degrees while the maximum size would be 0.49 degrees.