JEE MainPhysicsElectromagnetic Waves
The magnetic field of a plane electromagnetic wave is given by: B = 3 10⁻⁸ (ky + t) i T What is the corresponding vector equation for the electric field E ? (Speed of light in vacuum c = 3 10^8 m/s)
Options
- AE = 9 (ky + t) k V/m
- BE = -9 (ky + t) k V/m
- CE = -10⁻¹⁶ (ky + t) k V/m
- DE = -9 (ky + t) j V/m
Correct answer
B. E = -9 (ky + t) k V/m
Step-by-step solution
The given magnetic field is B = 3 10⁻⁸ (ky + t) i T. The phase of the wave is (ky + t) . For a constant phase, ky + t = constant , which means the wave is propagating in the negative y -direction. Thus, the direction of propagation is S = - j . The direction of the magnetic field is B = i . The direction of wave propagation is given by S = E B . Substituting the known directions: - j = E i Since (- k ) i = - j , the direction of the electric field must be E = - k . The amplitude of the electric field is related to