At a distance of 20 m from a source of sound, the sound level is 40 db. if the observer backs up to a distance of 40 m from the source, what will the sound level be? o a. 34 db o b. 28 db ° c. 20 db o d. 10 db

This chart shows characteristics of three different types of waves. which statement is best supported by the information in the chart? wave x and wave y are mechanical waves, and wave z is an electromagnetic wave. wave x and wave y are electromagnetic waves, and wave z is a mechanical wave. wave x and wave z are electromagnetic waves, and wave y is a mechanical wave. wave x and wave z are mechanical waves, and wave y is an electromagnetic wave.