Answer:
8 s
Explanation:
The time, t it takes the wave to move from its crest highest point to its lowest point is half of its period, T.
That is t = T/2
Given that t = 4 s, and making T subject of the formula, we have
T = 2t
Substituting t = 4 s into T, we have
T = 2t
T = 2 × 4 s
T = 8 s
So, its period is 8 s