Final answer:
When the frequency of a wave is 10 Hz, its period is calculated as the reciprocal of the frequency, giving a period of 0.1 seconds.
Step-by-step explanation:
The frequency of a wave is defined as the number of wave cycles that pass a point per second, and it is measured in hertz (Hz). Conversely, the period of a wave is the time it takes for one complete wave cycle to pass a point. To find the period when the frequency is known, you can use the relationship that the frequency is the reciprocal of the period, which can be written as:
frequency (f) = 1 / period (T)
Therefore, when the frequency of a wave is 10 Hz, its period (T) is calculated as 1/10, which is 0.1 seconds (s). So, the correct answer to the question "The frequency of a certain wave is 10 hertz and its period is" is:
0.1 seconds (Option A).