A charged particle enters in parallel direction to an electric field and a magnetic field such that both fields are parallel to each other. Then force on the charge is:

Explanation

When a charged particle enters a region where both electric and magnetic fields are parallel and oriented in the same direction, the force experienced by the charge is a combination of both the electric and magnetic forces acting on it.The force on a charged particle in an electric field (E) is given by:F_electric = q * Ewhere q is the charge of the particle.The force on a charged particle moving with velocity (v) in a magnetic field (B) is given by:F_magnetic = q * v * BIn this case, since both fields are parallel and oriented in the same direction, the velocity of the particle and the direction of the magnetic force are the same. Therefore, the force due to the magnetic field can be written as:F_magnetic = q * v * B * sin(theta)where theta is the angle between the velocity of the particle and the magnetic field.Since the particle is moving parallel to both fields, theta is 0 degrees (or 180 degrees). In thissituation, the sine of 0 degrees (or 180 degrees) is zero:sin(0) = 0sin(180) = 0As a result, the force due to the magnetic field is zero in this case:F_magnetic = q * v * B * sin(theta) = q * v * B * 0 = 0Therefore, the total force experienced by the charged particle in this scenario is only due to the electric field:Total Force = F_electric = q * EThe magnetic force does not contribute to the overall force on the particle since the particle's velocity is parallel to the magnetic field lines.