NEET2026PhysicsChapterActual
The electric field of a plane electromagnetic wave propagating in free space is represented by E = 150 (1.5 10^3 z - 4.5 10¹¹ t ) j V/m . Which of the following expressions correctly represents the associated magnetic field vector?
Options
- A-5 10⁻⁷ (1.5 10^3 z - 4.5 10¹¹ t ) i T
- B5 10⁻⁷ (1.5 10^3 z - 4.5 10¹¹ t ) i T
- C5 10⁻⁷ (1.5 10^3 z - 4.5 10¹¹ t ) k T
- D4.5 10¹⁰ (1.5 10^3 z - 4.5 10¹¹ t ) i T
Correct answer
A. -5 10⁻⁷ (1.5 10^3 z - 4.5 10¹¹ t ) i T
Step-by-step solution
The given electric field is E = 150 (1.5 10^3 z - 4.5 10¹¹ t ) j V/m . Comparing this with the standard equation E = E₀ (kz - t) j , we get: Amplitude of electric field, E₀ = 150 V/m Angular frequency, = 4.5 10¹¹ rad/s Wave number, k = 1.5 10^3 m ⁻¹ The speed of the electromagnetic wave is c = k = 4.5 10¹¹ 1.5 10^3 = 3 10^8 m/s . The amplitude of the magnetic field is B₀ = E₀ c = 150 3 10^8 = 5 10⁻⁷ T . The phase of the wave is (kz - t) , which indicates that the wave is propagating in the +z direction ( k ). The d