문제자유공간에서 전파3aE(z,t)=10sin(ωt-βz)[V/m]y일 때 자파 H(z,t)[A/m]는?1310sintza(−)ωβz120π2310sin(t−z)aωβx120π3310−sin(t−z)aωβz120π4310sintza−(−)ωβx120π