Final answer:
The period of a thunder wave with a frequency of 100 Hz is 0.01 seconds, as period and frequency are inversely related.
Step-by-step explanation:
The frequency of a wave is the number of times a wave completes a cycle in one second, while the period is the time it takes for one complete cycle. To calculate the period of a wave when you know the frequency, you can use the relationship that the period T is the reciprocal of the frequency f. Therefore, for a thunder wave with a frequency of 100 Hz, the period T is 1 divided by the frequency. The period T = 1/f, so the period T is 1/100 seconds or 0.01 seconds.