The period of a wave is the time that it takes a wave to go from peak to peak. Therefore, to determine the period of the waves we need to find the quotient between the the time and the number of waves, like this:
[tex]T=\frac{t}{N}[/tex]Where "N" is the number of waves and "t" is the time. Plugging in the values we get:
[tex]T=\frac{3s}{6}=\frac{1}{2}s=0.5s[/tex]Therefore, the period is 0.5 seconds.
