申論題

1. Consider two uniform plane waves propagating in free space. The two waves are denoted by① and ②, respectively. The electric field of wave ① is . The electric field of wave @ is E =. The speed of light in free space is 3 X 10⁸ m/s.

(8) (5%) If the time-averaged power flow density of wave① is P₁, what is the time-averaged power flow density of wave②?