Answer: Their wavelength is comparable to or larger than obstacle dimensions.
- A Their wavelength is comparable to or larger than obstacle dimensions
- B They travel through air at a higher speed than short radio waves
- C They carry more photon energy than shorter-wavelength radio waves
- D They are always vertically polarized unlike shorter radio waves
Correct answer: A. Their wavelength is comparable to or larger than obstacle dimensions
Explanation: Diffraction is significant when wavelength ≳ obstacle size. Long radio waves (km wavelengths) diffract around mountains and curve with Earth. Short waves (MHz range) require line-of-sight or reflection.
In an electromagnetic wave, the oscillating electric field (E) and magnetic field (B) are perpendicular to each other and to the direction the wave travels - a purely transverse wave that needs no medium, unlike sound.
Concept context
Maxwell's equations, EM spectrum, properties, and applications of each band.