If a particle is moving in a region of both electric & magnetic fields then the total force acting on it is:

Explanation

Option A is correct.The total force acting on a particle moving in a region of both electric and magnetic fields is called the Lorentz force. It is given by the following equation: F = q(E + v × B) where: F is the force (N) q is the charge of the particle (C) E is the electric field strength (V/m) v is the velocity of the particle (m/s) B is the magnetic field strength (T) The electric force is given by the following equation: F = qE The magnetic force is given by the following equation: F = qvB sin θ where: θ is the angle between the direction of the velocity and the direction of the magnetic field (°) As you can see, the Lorentz force is the sum of the electric force and the magnetic force. The electric force is proportional to the charge of the particle and the electric field strength. The magnetic force is proportional to the charge of the particle, the velocity of the particle, and the magnetic field strength. The direction of the Lorentz force is the same as the direction of the electric force if the velocity of the particle is parallel to the magnetic field. The direction of the Lorentz force is perpendicular to the direction of the velocity and the direction of the magnetic field if the velocity of the particle is not parallel to the magnetic field