Propagation of EM waves

Light travels through a thick glass slab with a speed of . It travels at a velocity $\mathbf{v}=2.00\times {10}^8{\displaystyle \frac{\text{m}}{\text{s}}}(-\hat{k})$‍. In the path of the light, at a certain point and at a certain time, the magnetic field is observed to be $\mathbf{B}=1.50\times {10}^{-3}\text{T}(-\hat{i})$‍.