Chapter-4|Moving Charges and Magnetism| NCERT 12th Physics:
Magnetic Force on a Current Carrying Conductor (In a Uniform Magnetic Field):
We know that a moving charge particle experiences a magnetic force in a magnetic field and the value of force is F= q(V×B).
A current carrying wire has a chargers moving inside it opposite direction of current, So when a current carrying wire placed in a magnetic field, it experiences a force and deflect due to total force on all moving charges.
Let we consider a current carrying conductor of length l and cross-sectional area A of a straight conductor carrying a current I.
Total force F on the free electrons
Direction of Force:
(I) Right hand Palm Rule: Put thumb in the direction of current and all fingers in the direction of magnetic field, then the force F will be perpendicular to the Palm in the direction of pushing by the palm.
(II) Fleming’s Left hand Fule: Firstly put your thumb, forefinger and middle finger perpendicular to each other. Adjust your fore finger in the direction of magnetic field and middle finger in the direction of current, Now your thumb will represent the direction of force.