The period is the duration of time of one cycle in a repeating event so the period is the reciprocal of the frequency. The wave period is the measure of time it takes for the wave cycle to complete. A particular time period for which data is gathered and used as a benchmark against which economic data from other periods is measured.
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Elements in the same period all have the same highest unexcited electron energy level or same ground state energy level. A well-proportioned sentence of several clauses. Or In the decimal value system a set of huge numbers will be separated in pairs of three using comma symbol. In large numbers periods are groups of three digits separated by commas.