Correct Answer - Option 3 : 3.33 × 10

^{-7} T

__Concept__:

The intrinsic impedance of the wave is defined as the ratio of the electric field and the magnetic field phasor (complex amplitude), i.e.

\(η =\frac{E}{H}\)

For free-space, the intrinsic impedance is a real quantity, i.e.

η = η0 = 120π

__Analysis__:

E = Emax sin(Kx - ωt)

With E_{max} = 100 N/C, the magnetic field will be:

With \(η =\frac{E}{H}\):

\(H =\frac{E}{\eta}\)

\(H =\frac{100}{120\pi}A/m\)

B = μ_{0} H

\(B=4\pi × 10^{-7}× \frac{100}{120\pi }\)

**B = 3.33 × 10**^{-7} T