The Reconstruction Finance Corporation (RFC) was established during the Hoover administration with the primary objective of providing liquidity to, and restoring confidence in the banking system. The banking system experienced extensive pressure during the economic contraction of 1929-1933.
Typical materials used for electromagnetic shielding include sheet metal, metal screen, and metal foam. Any holes in the shield or mesh must be significantly smaller than the wavelength of the radiation that is being kept out, or the enclosure will not effectively approximate an unbroken conducting surface.
Electromagnetic waves are waves of energy formed by accelerating charge. They are classified by the wavelength, frequency, and energy. The electromagnetic spectrum is an illustration of such classification. At one end of the spectrum are the longer wavelength, lower frequency, and lower energy waves. At the other end are the shorter wavelength, higher frequency, and higher energy waves. The spectrum in order from the lower frequency to the higher frequency is radio waves, microwaves, infrared, visible light, ultraviolet, x-ray, and gamma ray.