The electric field component of a uniform plane wave propagating in a lossless magnetic dielectric medium is given by $$\overrightarrow E \left( {t,\,z} \right) = {{\hat a}_x}5\cos \left( {{{10}^9}t - \frac{{20}}{3}z} \right){\text{V/m}}{\text{.}}$$       If η₀ represents the intrinsic impedance of the free space, the corresponding magnetic field component is given by

A. $$\overrightarrow H \left( {t,\,z} \right) = {{\hat a}_y}\frac{5}{{2{\eta _0}}}\cos \left( {{{10}^9}t - \frac{{20}}{3}z} \right){\text{A/m}}$$

B. $$\overrightarrow H \left( {t,\,z} \right) = {{\hat a}_y}\frac{{10}}{{{\eta _0}}}\cos \left( {{{10}^9}t - \frac{{20}}{3}z} \right){\text{A/m}}$$

C. $$\overrightarrow H \left( {t,\,z} \right) = {{\hat a}_z}\frac{{10}}{{2{\eta _0}}}\cos \left( {{{10}^9}t - \frac{{20}}{3}z} \right){\text{A/m}}$$

D. $$\overrightarrow H \left( {t,\,z} \right) = {{\hat a}_z}\frac{{10}}{{{\eta _0}}}\cos \left( {{{10}^9}t - \frac{{20}}{3}z} \right){\text{A/m}}$$

Answer: Option B