uniform plane wave$$ E $=$ E$0(1+$ j$)$ e$$jz $$ax$,$ operating at a frequency $2$ GHz$,$ propa$-$

gates in a dielectric of r $=4$ and r $=1.$ Find

$($a$)$ wavelength,

$($b$)$ the real instantaneous value $($as cosine$)$ of$$ E and$$ H