F: Lorentz force or ampere force, Q: charge amount, V: speed, E: electric field strength, φ (= δ BS or bδ S, b is magnetic induction strength, s is area): magnetic flux, s: area. It can be seen from the formula that not only the magnetic flux but also the curved surface affects the magnetic field strength. So it's not magnetic flux, but magnetic force.
2. Definition of magnetic induction intensity: The electric field force that the charge receives in the electric field is certain, and the direction is the same as or opposite to the electric field direction at this point. The magnetic field force (ampere force) that the current receives somewhere in the magnetic field is related to the direction in which the current is placed in the magnetic field. When the current direction is parallel to the magnetic field direction, the ampere force on the current is the smallest, which is equal to zero. When the current direction is perpendicular to the magnetic field direction, the ampere force of the current is the largest. When the point charge Q moves at the speed V in the magnetic field, it is acted by a force F. Under a given magnetic field, the magnitude of F is related to the direction of charge movement. When v is in a special direction or the opposite direction, the force is zero; When V is perpendicular to this special direction, the maximum force is Fm. Fm is proportional to |q| and v, and the ratio has nothing to do with the moving charge, but reflects the nature of the magnetic field itself, which is defined as the magnitude of the magnetic induction intensity, that is. The direction of B is defined as the forward direction of the right hand spiral when the direction of the maximum force Fm on the positive charge turns to the direction of the charge moving V. After defining B, the force on the moving charge in the magnetic field B can be expressed as F= QVB, which is the Lorentz force formula.