JEE MainPhysicsElectromagnetic Waves
The electric field of an electromagnetic wave propagating in vacuum is given by E = 30 (2 10^3 y - 6 10¹¹ t) i V/m . The corresponding magnetic field vector B is
Options
- A10⁻⁷ (2 10^3 y - 6 10¹¹ t) k T
- B-10⁻⁷ (2 10^3 y - 6 10¹¹ t) k T
- C-9 10^9 (2 10^3 y - 6 10¹¹ t) k T
- D9 10^9 (2 10^3 y - 6 10¹¹ t) k T
Correct answer
B. -10⁻⁷ (2 10^3 y - 6 10¹¹ t) k T
Step-by-step solution
The direction of wave propagation v is determined from the phase (ky - t) , which indicates the +y direction. Thus, v = j . The electric field is along the +x direction, so E = i . The direction of the magnetic field B can be found using the relation E B = v . Substituting the known directions: i B = j . Since i (- k ) = j , the magnetic field must be along the -z direction ( - k ). The amplitude of the magnetic field is given by B₀ = E₀ c . B₀ = 30 3 10^8 = 10⁻⁷ T . Therefore, the magnetic field vector is B = -10⁻