If `E` and `B` represent electric and magnetic field vectors of the electromagnetic wave, the direction of propagation of eletromagnetic wave is along.

Options

A. `vec(E)`
B. `vec(B)`
C. `vec(B) xx vec(E)`
D. `vec(E) xx vec(B)`

Explanation

To determine the direction of propagation of an electromagnetic wave given the electric field vector \( \mathbf{E} \) and the magnetic field vector \( \mathbf{B} \), we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Orientation of Fields**:
- In an electromagnetic wave, the electric field \( \mathbf{E} \) and the magnetic field \( \mathbf{B} \) oscillate perpendicular to each other. This means that if you visualize the wave, the electric field might oscillate in one plane, while the magnetic field oscillates in a plane that is perpendicular to it.

2. **Identify the Direction of Propagation**:
- The direction of propagation of the electromagnetic wave is given by the cross product of the electric field vector \( \mathbf{E} \) and the magnetic field vector \( \mathbf{B} \). Mathematically, this is represented as:
\[ \text{Direction of propagation} = \mathbf{E} \times \mathbf{B} \]

3. **Visualize the Cross Product**:
- To visualize the direction of \( \mathbf{E} \times \mathbf{B} \), you can use the right-hand rule. Point your fingers in the direction of \( \mathbf{E} \) and curl them towards \( \mathbf{B} \). Your thumb will then point in the direction of the wave's propagation.

4. **Conclusion**:
- Therefore, the direction of propagation of the electromagnetic wave is along the vector \( \mathbf{E} \times \mathbf{B} \).

### Final Answer:
The direction of propagation of the electromagnetic wave is along \( \mathbf{E} \times \mathbf{B} \).

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