The electric field associated with an electromagnetic wave travelling in vacuum is given by E₀ sin(3y + 4z + ωt) î, where ω is the angular frequency. All quantities are in SI units. The correct statement(s) about this wave is/are: [Given: speed of light in vacuum c = 3 × 10⁸ m s⁻¹.]
Select all that apply

Question

The electric field associated with an electromagnetic wave travelling in vacuum is given by E₀ sin(3y + 4z + ωt) î, where ω is the angular frequency. All quantities are in SI units. The correct statement(s) about this wave is/are: [Given: speed of light in vacuum c = 3 × 10⁸ m s⁻¹.]

Select all that apply

G1 Physics · Accepted Answer

The phase is 3y + 4z + ωt. A positive sign before ωt means propagation opposite to the wave-vector direction, so the propagation direction is −(3ĵ + 4k̂)/5. The magnitude of the wave vector is √(3²+4²) = 5 m⁻¹, not 0.5 m⁻¹. Therefore ω = ck = (3 × 10⁸)(5) = 1.5 × 10⁹ rad s⁻¹. Hence A and C are correct.