JEE Main202621 January 2026Morning ShiftPhysicsElectromagnetic WavesActual
The electric field in a plane electromagnetic wave is given by : E_ y =69 [0.6 10³ x-1.8 10¹¹ t ] V / m . The expression for magnetic field associated with this electromagnetic wave is _ _ _ _ T.
Options
- AB_ z =2.3 10⁻⁷ [0.6 10³ x-1.8 10¹¹ t ]
- BB_ z =2.3 10⁻⁷ [0.6 10³ x+1.8 10¹¹ t ]
- CB_ y =69 [0.6 10³ x+1.8 10¹¹ t ]
- DB_ y =2.3 10⁻⁷ [0.6 10³ x-1.8 10¹¹ t ]
Correct answer
A. B_ z =2.3 10⁻⁷ [0.6 10³ x-1.8 10¹¹ t ]
Step-by-step solution
Given E_y = 69 [0.6 10^3 x - 1.8 10¹¹ t] V/m Wave propagates along +x (form kx - t ), E is along y. For EM wave: E B = direction of propagation j k = i , so B is along z-direction. B₀ = E₀ c = 69 3 10^8 = 2.3 10⁻⁷ T E and B are in phase for plane EM wave. B_z = 2.3 10⁻⁷ [0.6 10^3 x - 1.8 10¹¹ t] T