Question

TV waves have wavelength range of $1-10\, m$. 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 $\lambda_{1}=1 m, \lambda_{2}=10\, m$
Since, TV waves/are electromagnetic, so they may have speed equal to that of light, i.e.,
$c=3 \times 10^{8} m / s$
$\therefore f_{1}=\frac{c}{\lambda_{1}}=\frac{3 \times 10^{8}}{1}=3 \times 10^{8}=300 \,MHz$
and $f_{2}=\frac{c}{\lambda_{2}}=\frac{3 \times 10^{8}}{10}=0.3 \times 10^{8}=30 \,MHz$
Hence, frequency ranges from $30 \,MHz$ to $300 \,MHz .$