Question

two sinusoidal sound waves with slightly different frequencies combine to form a third sound wave called a beat. how does the amplitude of the best change over time or does it remain constant?
a. the amplitude increases indefinitely
b. the amplitude changes in a pattern of steady increase, then sudden decrease
c. the amplitude increases and decreases in a sinusoidal pattern.
d. the amplitude remains constant

Answer 1

Two sinusoidal sound waves with slightly different frequencies combine to form a third sound wave called a "beat".

How does the amplitude of a best change over time or does it remain constant?

$\Rightarrow$ the amplitude increases and decreases in a sinusoidal pattern

option (c) : it will be correct.

Explanation - Beats are a phenomenon which caused by the superposition of two waves that have slightly different frequencies. These waves can be of any shape and they do not have to be the same amplitude, but the case of two sinusoidal waves of equal amplitude makes a good illustration.