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A charged particle moving in a constantmagnetic field always experiences a magnetic force, regardless of its direction of motion. • may experience a magnetic force which will cause its speed to change. • may experience a magnetic force, but its speed will not change

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Answer:

A charged particle moving in a constant magnetic field may experience a magnetic force but its speed will not change.

Step-by-step explanation:

The magnetic force experienced by a charged particle q that moves in a magnetic field
\vec{B} with velocity
\vec{v} is:


\vec{F}=q\vec{v}\ x\ \vec{B}

and its magnitude is given by:


F=q\ v \ B \sin \theta

where
\theta is the angle between the magnetic field and the velocity.

There are two special cases:

  • If
    v and
    B are parallel
    \theta=0 or opposite
    \theta=\pi then
    sin\ \theta=0. If the particle moves along magnetic field lines it won't experience a magnetic force.
  • If the angle between
    v and
    B is
    \theta=(\pi)/(2) the magnetic force has a maximum.

The magnetic force is always perpendicular to the velocity. The work
W done by the magnetic force is equal to the force
\vec{F} multiplied by the displacement
\vec{dr} in the direction of the force:


W=\vec{F}.\vec{dr}=\vec{F}.(\vec{v}.\Delta t)=0

Given that the work is equal to the change in kinetic energy
W=\Delta K and
K \approx (1)/(2) mv^(2) this means the speed will not change.

User Ninja Dude
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