let us study about work done by magnetic force
on a moving charge. as, we know we already
can see the direction of magnetic force is
perpendicular to velocity as well as that
of magnetic induction. so here we can write
as. this magnetic force vector. is always.
perpendicular to velocity vector. so. this
magnetic force. can never do any work. on,
freely moving. charge particle. because if
force is acting in a direction perpendicular
to velocity in the direction of force there
will be never any displacement. so for freely
moving particles we can always state that
magnetic force can never do any work. and
hence we can say. in magnetic field. speed
of. any moving charge particle. can never
be changed. due to. magnetic force. it is
quite obvious that if magnetic force can not
do any work on a moving charge particle in
magnetic field. so it can never supply any
kinetic energy to the charge particle hence
speed of any moving charge particle in magnetic
field can never change due to magnetic force,
so just remember the fact about, the work
done by magnetic force, which is always equal
to zero.
