Question

the magnetic force on a charged particle is in the direction of its velocity if
a) it is moving in the direction of the field
b)it is moving opposite to the direction of the field
c( it is moving prependicular to field
d)it is moving in some other direction
e)never ​

Answer 1

Answer:

c( it is moving prependicular to field

Answer 2

Answer:

The correct answer is option e.

Explanation:

The magnetic force on a charged particle is given by Lorentzian force,

$\(\vec F=q(\vec E+\vec v\times \vec B)$

where

$\vec F$  is the force acting on the particle

q is the charge of the particle

$\vec v$ is the velocity

$\vec E$ is the electric field

$\vec B$ is the magnetic field

From the equation, it is clear that

• The force $\vec F$  acting on the particle is always perpendicular to both the velocity $\vec v$ and the magnetic field $\vec B$.
• Hence the magnitude of the force is given by $F = qvB sin\theta$ , where θ is the angle between the velocity and the magnetic field.
• If $\theta=0^{o} or 180^{o}$, the magnetic force on a stationary charge or a charge moving parallel to the magnetic field is zero.

Therefore, if there is any force acting and the charge is moving with certain velocity in the magnetic field, they must be perpendicular to each other, otherwise it is zero.

Therefore, the correct answer is option e.