A plane electromagnetic wave travels in vacuum along z-direction. What will be the directions of its electric field ($\vec E$) and magnetic field ($\vec B$) vectors?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → $\vec E$ and $\vec B$ in x-y plane and are mutually perpendicular
For a plane electromagnetic wave propagating in vacuum along z-direction:
1. The electric field $\vec{E}$ and magnetic field $\vec{B}$ are both perpendicular to the direction of wave propagation (z-axis).
2. $\vec{E}$ and $\vec{B}$ are perpendicular to each other.
3. Right-hand rule: if wave propagates along z, $\vec{E}$ along x, then $\vec{B}$ along y.
Directions: $\vec{E}$ ⊥ z (say along x), $\vec{B}$ ⊥ z and ⊥ $\vec{E}$ (say along y), wave propagates along z