The cross product `vecExxvecB` (where `vecE` =electric field vector and `vecB` is the magnetic field vector ) always gives the.............. of electromagnetic wave.

Answer

To solve the question regarding the cross product of the electric field vector \(\vec{E}\) and the magnetic field vector \(\vec{B}\) in an electromagnetic wave, let's break it down step by step.

### Step-by-Step Solution:

1. **Understanding the Cross Product**:
The cross product \(\vec{E} \times \vec{B}\) is a vector operation that results in a vector that is perpendicular to both \(\vec{E}\) and \(\vec{B}\). This is a fundamental property of the cross product.

2. **Direction of the Vectors**:
In an electromagnetic wave, the electric field vector \(\vec{E}\) and the magnetic field vector \(\vec{B}\) are both perpendicular to the direction of wave propagation. If we visualize this in a three-dimensional coordinate system, we can assign directions to these vectors.

3. **Using the Right-Hand Rule**:
To determine the direction of the resultant vector from the cross product \(\vec{E} \times \vec{B}\), we can use the right-hand rule. Point your fingers in the direction of \(\vec{E}\), curl them towards \(\vec{B}\), and your thumb will point in the direction of the resultant vector, which represents the direction of wave propagation.

4. **Conclusion**:
The cross product \(\vec{E} \times \vec{B}\) gives the direction of propagation of the electromagnetic wave. Therefore, the answer to the question is that the cross product \(\vec{E} \times \vec{B}\) always gives the **direction of propagation of the electromagnetic wave**.

### Final Answer:
The cross product \(\vec{E} \times \vec{B}\) always gives the **direction of propagation of the electromagnetic wave**.