what is the si unit of time period
Frequency The SI derived unit of frequency is the hertz (Hz), named after the German physicist Heinrich Hertz. One hertz means that an event repeats once per second. A previous name for this unit was cycles per second (cps). The SI unit for period is the second.
Obsolete German units of measurement The metric system became compulsory on January 1, 1872, in Germany and on January 1, 1876, in Austria.[1]