The electric field part of an electromagnetic wave in a medium is represented by Ex = 0 Ey=2.5N/C cos[(2π × 106rad/s)t−(π × 10−2rad/mx)]

 We know that the standard equation of electromagnetic wave is given by:

Ey = E0cos(wt−kx)

The equation that is given is: Ey=2.5N/C cos[(2π × 106rad/s)t−(π × 10−2rad/mx)]

Now we have to compare the given equation with the standard equation.

On the comparison, we get that:

⇒ w=2πf

⇒ w = 2π×106

⇒ λf = 106Hz

It is also known to us that: 2πλ=k=π×10−2m−1

⇒ f = λ=200m

Hence we can say that the wave is moving along the positive x direction with a frequency of 106Hz and a wavelength of 200 m.