Question

the poynting vector of an electromagnetic wave is given by S=2i+ 4j+ ?5 k. find the angle made by direction of propagation with X axis

Answer 1

Dear Student,
$$\begin{gathered} heredirectionofpointingvecorissameasdirectionofpropogationofthewave \\ soanglemadebyvectorSwithx-axiswillbegivenby \\ \cos \left(\alpha \right)=\frac{2}{\sqrt{2^2+4^2+5^2}}=\frac{2}{\sqrt{45}} \\ or \\ \alpha ={\cos }^{-1}\left(\frac{2}{\sqrt{45}}\right) \end{gathered}$$
Regard