NEETPhysicsElectromagnetic Waves
The electric field of a plane electromagnetic wave propagating in a transparent non-magnetic medium is given by E = 40 (1.2 10^8 t - 0.6 z) i V/m . The corresponding magnetic field equation will be:
Options
- A2 10⁻⁷ (1.2 10^8 t - 0.6 z) j T
- B1.33 10⁻⁷ (1.2 10^8 t - 0.6 z) j T
- C-2 10⁻⁷ (1.2 10^8 t - 0.6 z) j T
- D8 10^9 (1.2 10^8 t - 0.6 z) j T
Correct answer
A. 2 10⁻⁷ (1.2 10^8 t - 0.6 z) j T
Step-by-step solution
Given the electric field equation: E = 40 (1.2 10^8 t - 0.6 z) i V/m Comparing with the standard equation E = E₀ ( t - kz) i , we get: E₀ = 40 V/m = 1.2 10^8 rad/s k = 0.6 rad/m The speed of the wave in the medium is: v = k = 1.2 10^8 0.6 = 2 10^8 m/s The amplitude of the magnetic field is: B₀ = E₀ v = 40 2 10^8 = 2 10⁻⁷ T The wave propagates in the +z direction (since the phase is t - kz ), so v = k . The direction of the magnetic field is given by E B = v . i B = k B = j Therefore, the magnetic field equation is: