A charged particle experience magnetic force in the presence of magnetic field. Which of the following statement is correct?

Options

A. the particle is moving and magnetic field is perpendicular to the velocity
B. The particle is moving and magnetic fiels is parallel to the velocity
C. The particle is stationary and magnetic field is perpendicular to the velocity
D. The particle is stationary and magnetic field is parallel to the velocity

Answer

To determine which statement is correct regarding the magnetic force experienced by a charged particle in a magnetic field, we can analyze each option based on the principles of electromagnetism.

### Step-by-Step Solution:

1. **Understanding the Magnetic Force Formula**:
The magnetic force \( F \) on a charged particle moving in a magnetic field is given by the equation:
\[ F = Q \cdot v \cdot B \cdot \sin(\theta) \]
where:
- \( F \) is the magnetic force,
- \( Q \) is the charge of the particle,
- \( v \) is the velocity of the particle,
- \( B \) is the magnetic field strength,
- \( \theta \) is the angle between the velocity vector and the magnetic field vector.

2. **Analyzing Each Option**:
- **Option A**: The particle is moving and the magnetic field is perpendicular to the velocity.
- Here, \( \theta = 90^\circ \) (since they are perpendicular).
- Thus, \( \sin(90^\circ) = 1 \).
- Therefore, the force \( F = Q \cdot v \cdot B \), which is not zero if \( Q \), \( v \), and \( B \) are non-zero. This option is correct.

- **Option B**: The particle is moving and the magnetic field is parallel to the velocity.
- Here, \( \theta = 0^\circ \).
- Thus, \( \sin(0^\circ) = 0 \).
- Therefore, the force \( F = Q \cdot v \cdot B \cdot 0 = 0 \). This option is incorrect.

- **Option C**: The particle is stationary and the magnetic field is perpendicular to the velocity.
- Here, if the particle is stationary, \( v = 0 \).
- Thus, \( F = Q \cdot 0 \cdot B \cdot \sin(\theta) = 0 \). This option is incorrect.

- **Option D**: The particle is stationary and the magnetic field is parallel to the velocity.
- Again, since the particle is stationary, \( v = 0 \).
- Thus, \( F = Q \cdot 0 \cdot B \cdot \sin(\theta) = 0 \). This option is incorrect.

3. **Conclusion**:
The only option where the charged particle experiences a non-zero magnetic force is **Option A**: "The particle is moving and the magnetic field is perpendicular to the velocity."

### Final Answer:
The correct statement is **Option A**.