Question

How can magnetic force be reduced?

Answer 1

Hint: The magnetic force experienced by an object equal to charge multiplied by the cross or vector product of object’s velocity and magnetic field intensity. Magnetic force can be reduced by changing the charge, the object’s velocity or the magnetic field intensity.

Complete answer:
Magnetic force is the force which arises due to the motion of charges. The force experienced by an object, say a charge due to the motion of another charge is called magnetic force.
The formula for magnetic force is given by,
$\vec{F}=q(\vec{v}\times \vec{B})$ ….(i)
Where, q is the magnitude of the charge, $\vec{v}$ is the velocity of the object (another charge) and $\vec{B}$is the magnetic field intensity.
The figure below shows the velocity of the object $\vec{v}$ and magnetic field intensity$\vec{B}$, the angle between them is $\theta $ and the vector $(\vec{v}\times \vec{B})$ shows the direction of the cross product of the velocity of the object $\vec{v}$ and magnetic field intensity $\vec{B}$.

The direction of the magnetic force is the same as the direction of $(\vec{v}\times \vec{B})$ vector, which is perpendicular to both the velocity of the object $\vec{v}$ and magnetic field intensity $\vec{B}$.
To reduce magnetic force, we can use three methods, as follows,
Reduce the charge q, as charge is directly proportional to magnetic force, according to equation (i).
Reduce the magnetic field intensity $\vec{B}$, as magnetic field intensity is directly proportional to magnetic force, according to equation (i).
Reduce the velocity of the object $\vec{v}$, as the velocity of the object is directly proportional to magnetic force, according to equation (i).
Using the above mentioned methods the magnetic force can be reduced.

Note:
The formula of magnetic force is used in many places in electrostatics so should be kept in mind. The direction of magnetic force is found by Fleming’s right-hand rule, where the thumb represents magnetic force, the fore finger represents magnetic field intensity and the middle finger represents current.