Question

TV waves have wavelength range of $1-10m$. Their frequency range will be:

• A. 3-30 MHz
• B. 30-300 MHz
• C. 3-3000 MHz
• D. 300-3000 MHz

Answer 1

Answer: (B)

TV waves range from wavelength ${\lambda }_1$ to ${\lambda }_2$.
Let ${\lambda }_1=1m,{\lambda }_2=10m$
Since, TV waves/are electromagnetic, so they may have speed equal to that of light, i.e.,
$c=3\times 10^{8}m/s$
$\therefore f_1=\frac{c}{{\lambda }_1}=\frac{3\times 10^8}{1}=3\times 10^8=300MHz$
and $f_2=\frac{c}{{\lambda }_2}=\frac{3\times 10^8}{10}=0.3\times 10^8=30MHz$
Hence, frequency ranges from $30MHz$ to $300MHz.$