Project Seafarer was an ambitious program to construct an enormous antenna, buried underground on a site about 10000 km2 in area. Its purpose was to transmit signals to submarines while they were deeply submerged. If the effective wavelength were 4.8 × 103 Earth radii, what would be the (a) frequency and (b) period of the radiation emitted? Ordinarily, electromagnetic radiations do not penetrate very far into conductors such as seawater. Take the Earth's radius to be 6370 km.