Fleming ’ s left Hand Rule
If we stretch the thumb , the forefinger and the central finger if left hand in such a way that all three are perpendicular to each other , then if forefinger represents the direction of magnetic field , central finger represents the direction of current flowing through the conductor , then thumb will represent the direction of magnetic force .
Lorentz Force
The total force experienced by a charge moving inside the electric and magnetic fields is called Lorentz force . It is given by F = q ( E * v * B )
Motion of a Charged Particle in a Uniform Magnetic Field When charged particle enter normal to the magnetic field it follows a circular path .
The radius of the path , r = mv / Bq
∴ r ∝ mv and r ∝ 1 / ( q / m )
Time period , T = 2πm / Bq
When charged particle enter magnetic field at any angle except 90 °, then it follows helical path .
The radius of the path , r = mv sin θ / Bq
The distance travelled by the charged particle in one time period due to component of velocity v cos θ , is called pitch of the path
Pitch = T * v cos θ = 2πmv cos θ / Bq