Period, T = 1/ f.
f = frequency = 200 Hz.
Period T = 1/200 = 0.005 seconds.
Well, one of the theories was that Charles darwin proved that theory evolution is real so that one theory.
The softest sound a human ear can hear is at 0dB. Sounds above 130dB causes pain.
By the use of "Solar cells" or "Solar panel", we can trap solar energy in silicon/germanium rods, then we can convert in into electricity too.
Hope this helps!