If a charge is moving in a magnetic field with velocity v, q(vXB) force acts on it. If a current carrying conductor is placed in a magnetic field, it experiences a force BiLsinθ (all symbols have usual meaning). But the reason behind the later force is the interaction between two magnetic fields;the one already existing and the one created by current. In my textbook, the derivation of this BiLsinθ force starts with Lorentz's force equation. How can we use that equation?? The cause of that force is not Lorentz force but the interaction of two fields. Also,why isn't the Hall effect seen in this case?? Why is it limited to specific materials only?