NEETPhysicsElectromagnetic Waves
The magnetic field of a plane electromagnetic wave in vacuum is given by: B = 2 10⁻⁸ (0.5 10^3 x + 1.5 10¹¹ t) j T Which of the following represents the corresponding vector equation for the electric field?
Options
- A6 (0.5 10^3 x + 1.5 10¹¹ t) (- k ) V/m
- B6 (0.5 10^3 x + 1.5 10¹¹ t) k V/m
- C6 (0.5 10^3 x + 1.5 10¹¹ t) i V/m
- D2 10⁻⁸ (0.5 10^3 x + 1.5 10¹¹ t) k V/m
Correct answer
B. 6 (0.5 10^3 x + 1.5 10¹¹ t) k V/m
Step-by-step solution
The phase of the wave is (kx + t) . Since both the x term and the t term have the same positive sign, the wave is propagating in the negative x -direction ( - i ). The direction of propagation is given by the cross product E B . We know the magnetic field B oscillates along the + j direction. Let the direction of the electric field be n . n j = - i Since k j = - i , the electric field must oscillate along the + k direction. The amplitude of the electric field E₀ is related to the magnetic field amplitude B₀ by: E₀