[tex]Dane:\\f_1 = 20 \ Hz = 20 \frac{1}{s}\\f_2 = 20 \ kHz = 20 \ 000 \ Hz = 20 \ 000 \frac{1}{s}\\v = 1224\frac{km}{h} = 1224\cdot\frac{1000 \ m}{3600 \ s} = 340\frac{m}{s}\\Szukane:\\a) \ \lambda_1 = ?\\b) \ \lambda_2= ?[/tex]
Rozwiązanie
Korzystamy ze wzoru na długość fali:
[tex]\lambda = v\cdot T\\\\gdzie\\\\T = \frac{1}{f}\\\\czyli\\\\\lambda = \frac{v}{f}[/tex]
[tex]a)\\\lambda_1 = \frac{v}{f_1}\\\\\lambda_1 = \frac{340\frac{m}{s}}{20\frac{1}{s}}\\\\\boxed{\lambda_1 = 17 \ m = 1 \ 700 \ cm}[/tex]
[tex]b)\\\lambda_2 = \frac{v}{f_2}\\\\\lambda_2 = \frac{340\frac{m}{s}}{20000 \frac{1}{s}}\\\\\boxed{\lambda_2 = 0,017 \ m\approx0,02 \ m}[/tex]
