Question

An audio signal of frequency 20Hz is to be radiated directly from transmitting antenna into the space. Then the approximate length of antenna (in km) is

• A. 3.75
• B. 37.5
• C. 375
• D. 3750

Answer 1

The correct option is D 3750

The length of the antenna is quarter of the wavelength.

$\frac{\lambda }{4}=\frac{c}{4\nu }=\frac{3\times {10}^5}{4\times 20}=3750km$