[tex]Dane:\\\lambda = 20 \ cm = 0,2 \ m\\v = 100\frac{m}{s}\\Szukane:\\f = ?\\\\\\\lambda = \frac{v}{f} \ \ /\cdot f\\\\\lambda\cdot f = v \ \ /:\lambda\\\\f = \frac{v}{\lambda}\\\\f = \frac{100\frac{m}{s}}{0,2 \ m}\\\\\boxed{f = 500 \ Hz}[/tex]
Odp. Częstotliwoć tej fali f = 500 Hz.
