The magnetic field of a plane EM wave is given by: B→ = B0 sin(kx−ωt)k^ This wave is traveling in the +x direction. The electric field of the wave would be given by: E→ = −cB0 sin(kx−ωt)j^ E→ = cB0 cos(kx−ωt)i^ E→ = −cB0 cos(kx−ωt)j^ E→ = cB0 sin(kx−ωt)j^ E→ = −cB0 sin(kx−ωt)k^