Answer: Travel long distances, can be reflected by the ionosphere, and carry modulated information.
- A Travel long distances, can be reflected by the ionosphere, and carry modulated information
- B Travel at exactly twice the speed of light in vacuum under all conditions in many documented cases
- C Pass through every obstacle in their path with zero attenuation or scattering according to conventional understanding
- D Are directly visible to the unaided naked human eye like ordinary sunlight in routine practice
Correct answer: A. Travel long distances, can be reflected by the ionosphere, and carry modulated information
Explanation: Radio waves (long wavelength) can travel around the Earth by ionospheric reflection, and carry information through amplitude (AM) or frequency (FM) modulation.
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.