1. I know that 1/2 of the real part of the complex poynting vector gives the average power flow per unit area. But what is the significance of its imaginary part ? 2. What is the significance of the complex intrinsic impedance ? For lossless medium (i.e. with no ohmic losses) it is real , but in circuit theory real impedance signifies ohmic losses. Then how the concept differs in both cases ? And also tell the significance of both the real and imaginary part of complex intrinsic impedance ?