[" 18.The maguitudes of Poynting vector and "],[" electric fleld vector are respectively "S" and "E" ."],[" then "],[[" 1."S=E^(2)sqrt((varepsilon_(0))/(mu_(0)))," 2."S=E^(2)sqrt(R_(0)mu_(0))],[" 3."S=E^(2)sqrt((mu_(0))/(varepsilon_(0)))," 4."S^(2)=(E^(2))/(mu_(0))],[," INTENSTY "]]