試題詳解

59. Which of the following statements about electromagnetic (EM) waves radiated from a point source with a fixed power is correct?
(A) The amplitude of the electric field strength of the EM wave decays with distance squared.
(B) The power received by a detector placed along the radial direction decays with distance.
(C) The energy flux density decays with distance squared.
(D) The larger the power radiated by the source is, the shorter the wavelength of the EM wave is.
(E) The amplitude of the magnetic field strength of the EM wave does not depend on distance.