Question

o antena semiunda emite in vid unde electromagnetice avand frecventa V=60MHz. Sa se afle a)lungimea de unda ;b) lungimea antenei ;c)viteza undelor in benzen (Er=2,25 miur= 1)

Answer 1

$\nu=60 MHz=6*10^7 Hz\\\lambda=\frac{c}{\nu}= \frac{3*10^8}{6*10^7}= 5 m=>\lambda=5 m\\l=\frac{\lambda}{2}=\frac{5}{2}=2,5 m =>l=2,5 m\\c=\frac{1}{\sqrt{\epsilon_o \mu_o} } \\v=\frac{1}{\sqrt{ \epsilon*\mu} } =\frac{1}{\sqrt{ \epsilon_o \epsilon_r\mu_o\mu_r}}=\frac{c}{\sqrt{ \epsilon_r\mu_r}}=\frac{3*10^8}{\sqrt{2,25*1}}= 2*10^8m/s =>v=2*10^8 m/s$