Question

Radio waves diffract pronoucedly around buildings, while light waves, which are electromagnetic waves, do not. Why?

Answer 1

Since phenomenon of diffraction is observed only when size of the obstacle is comparable to the wavelength of the wave. The wavelength of radio waves (particularly short waves) have wavelength comparable to general objects like buildings and hence easily get diffracted. But wavelength of light is very small (3900 Å to 7800 Å). So they are not diffracted.