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Question:

A plane electromagnetic wave travels in free space along the x-direction. The electric field component of the wave at a particular point of space and time is E = 6 Vm⁻¹ along y-direction. Its corresponding magnetic field component, B would be

6×10⁻⁸T along x-direction

6×10⁻⁸T along z-direction

2×10⁻⁸T along y-direction

2×10⁻⁸T along z-direction

Solution:

Correct option is C. 2×10⁻⁸T along z-direction
The direction of propagation of an EM wave is the direction of E→ × B→.
i^ = j^ × B^
B^ = k^
C = E/B ⇒ B = E/C = 6/(3 × 10⁸)
B = 2 × 10⁻⁸T along z-direction.