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### Forces on charged particles in electric and magnetic field

Things you should know

(A) If a charged particle is following a circular path of radius r under the influence of perpendicular electric field for example in case of electron moving around nucleus in an atom then,

(1) the force on the charged particle is inversely proportional to the square of radius of the circular path F α 1/r2

(2) The velocity of charged particle is inversely proportional to the square of the radius of circular path v α 1/√r

(3) The square of time period of revolution the charged particle is directly proportional to the cube of radius of circular path T2α r3

(B) When a charge particle is projected perpendicular to the magnetic field,

(1) It’s path is circular in plane perpendicular to the plane of magnetic field and direction of motion of charged particle.

(2) The speed and kinetic energy of particle would remain constant

(3) The velocity of charged particle only changes its direction not its magnitude

(4) The force acting on charged particle is independent of the radius of circular path but depends on the velocity of charged particle.

(5) The time period of revolution is independent of both velocity and radius of circular path of the particle.

(C) The net magnetic force on a current loop in a uniform magnetic field is zero but torque may or may not be zero

(D) The net magnetic force on a current loop in a non-uniform magnetic field is not zero but torque may or may not be zero.

(E) The torque on the coil is maximum , when the coil is suspended in the radial magnetic field.