Given a planar electromagnetic wave in vacuum whose B-field is denoted by

Question

Bx = 0, Bz = 0, B_y = 66.7 × 〖10〗^(-8) sin 4π〖10〗^6 (z-3×〖10〗^8 t)
Write an expression for the E-field. What are wavelength, speed and direction of motion of the disturbance?