Direction of Magnetic Field
The direction of magnetic field is determined with the help of the following simple laws:
Right hand thumb rule
According to this rule if a straight current carrying conductor is held in the right hand such that the thumb of the hand represents the direction of current flow, then the direction of folding fingers will represent the direction of magnetic lines of force (Fig. 9).
Right hand thumb rule of circular currents
According to this rule, if the direction of current in circular conducting coil is in the direction of folding fingers of right hand, then the direction of magnetic field will be in the direction of stretched thumb (Fig. 10).
Right hand palm rule
If we stretch our right hand such that the fingers point toward the point at which magnetic field is required while thumb is in the direction of current, then the normal to the palm will show the direction of magnetic field (Fig. 11).