An electromagnetic wave characterized by \(\vec{E}=30\pi {{e}^{i(\omega t-\frac{4}{3}y)}}\hat{k}\) , \(\vec{H}=\pi {{e}^{i(\omega t-\frac{4}{3}y)}}\hat{i}\) is propagating in a homogeneous non-conducting region where, \(\mu_r=1\), the value of \(\epsilon_r\) will be