In a region, steady and uniform electric and magnetic fields are present . These two fields are parallel to each other. A charged particle is released from rest in this region . The path of the particle will be a

Options

A. Helix
B. Straight line
C. Ellipse
D. Circle

Explanation

To solve the problem, we need to analyze the motion of a charged particle in the presence of both electric and magnetic fields that are parallel to each other.

### Step-by-Step Solution:

1. **Understanding the Fields**:
- We have a uniform electric field (E) and a uniform magnetic field (B) that are parallel to each other in a given region.
- Let's denote the electric field direction as positive along the x-axis.

2. **Charged Particle Released from Rest**:
- A charged particle (let's assume it has a positive charge +Q) is released from rest in this region.
- Since it starts from rest, its initial velocity (V) is 0.

3. **Force due to Electric Field**:
- The force acting on the charged particle due to the electric field is given by:
\[ F_E = Q \cdot E \]
- This force will act in the direction of the electric field (along the x-axis).

4. **Force due to Magnetic Field**:
- The force acting on the charged particle due to the magnetic field is given by the Lorentz force equation:
\[ F_B = Q \cdot (V \times B) \]
- Since the particle starts from rest, its initial velocity \( V = 0 \). Therefore, the magnetic force at the moment of release is:
\[ F_B = Q \cdot 0 \cdot B = 0 \]
- This means that initially, the magnetic field does not exert any force on the particle.

5. **Resultant Force**:
- Since the only force acting on the particle at the moment of release is the electric force \( F_E \), the particle will start to accelerate in the direction of the electric field.

6. **Path of the Particle**:
- As the particle accelerates due to the electric field, it will continue to move in a straight line along the direction of the electric field.
- The magnetic field does not influence the path at the moment of release because the velocity is zero and the forces are parallel.

### Conclusion:
The path of the charged particle will be a straight line in the direction of the electric field.