Question

Radio wave diffract around building although light waves do not. The reason is that radio waves

• A. Travel with speed larger than $c$
• B. Have much larger wavelength than light
• C. Carry news
• D. Are not electromagnetic waves

Answer 1

The correct option is B Have much larger wavelength than light

Diffraction only occurs when the wavelength of the wave is approximately equal to the obstacle size, i.e $\lambda \approx size$. As the size of the buildings will always remain constant we can say that diffraction will depend on the wavelength of the wave. Visible light has the wavelength in terms of ${10}^{-7}m$ which is much smaller than any building size. But the wavelengths of radio waves are much closer to the size of the buildings.

Hence, the correct answer is option (B), i.e the radio waves have much larger wavelength than visible light.