# ^Charge particle in magnetic field

**Charge particle in magnetic field**

A point charge moving in uniform magnetic field experiences a force on . Behaviour of charge particle depends on the angle ‘θ ‘ between .

**Case 1, if θ = 0 ^{0} or 180^{0} **

When the charged particle moves parallel or anti parallel to field then no net force acts on it & its trajectory remains a straight line.

**Case 2, If θ is other than 0 ^{0}, 180^{0} & 90^{0} **

Charge particle moves in a helical path of radius , completes one circle in time & travels a distance in one time period in the direction of field called pitch & is given by,

**Case 3, If θ is 90 ^{0}**

Charge particle moves in a circle at uniform speed.

Radius of circular path is

KE of particle is constant. It completes a cycle in time at angular frequency .

As the force acting on the particle is only normal & no tangential force is available thus speed & hence KE also of the particle will remain unchanged. As the kinetic energy of the charged particle remains constant. Hence no work is done in moving a charge particle moving at right angles to the magnetic field. However due to change in direction & are variables in direction.