3.0 Direction of force

  Magnetics

The direction of magnetic force can be obtained by either of the two rules, are
i. Right-hand rule
ii. Fleming's Left-hand rule preprocess

i. Right-hand rule :- If we wrap the fingers of the right hand around the line perpendicular to the plane of $\vec v$ and $\vec B$ so that they curl around with the sense of rotation, then thumb points in the direction of force $\vec F.$

NOTE :- Where $J=V$

ii. Fleming's Left-hand rule :- If we hold forefinger, middle finger and thumb of the left hand mutually perpendicular to each other; the forefinger shows the direction of $\vec B$ the middle finger shows the direction of the velocity of positive charge, then thumb indicates the direction of force.

NOTE :- Magnetic field can be represented by lines, called lines of field, just as the electric field. $\vec B$ is related to its line of induction in the following ways :
(i) The tangent drawn at any point to a line of field gives the direction of at that point.

(ii) The number of lines per unit area gives an idea about the magnitude of the magnetic field
vector $\vec B.$ This field is large if lines are closed and small if they are apart.