81. In a vacuum, a plane electromagnetic wave propagates. The amplitude of the magnetic field strength of the wave is 0.25 A / m. In its path, perpendicular to the direction of propagation, there is an absorbing surface, which has the form of a circle with a radius of 10 cm. What is the energy of absorption of this surface in a time of 1 min? The oscillation period T << t

Detailed solution. Decorated in Microsoft Word 2003. (Target decided to use formula editor)