Question

Why the force is maximum when a charged particle moves at right angles to the direction of magnetic field?

Answer 1

We know that F=m(v x B).
The cross product itself imples that the direction of the force is dependant on velocity and magnetic field and it is perpendicular to both of them. We know that v x B= vB sinx
So therefore the value is max when sinx=1 ie x=90°.
So it is understood that the force is max when the particle moves in right angle with direction of magnetic field...