ng diagram:We can calculate the field inside a solenoid with n turns per unit length using Ampre's Law:Summary:We have now examined how magnetic fields are created, and how to calculate their magnitude. Next, we will examine the force felt on moving charges and currents due to magnetic fields. Field --* Force on moving chargeWe know that a moving charge sets up a Magnetic Field. We also know that this field sets up a force on other moving charges. This force is perpendicular both to the magnetic field and to the velocity of the charge: Next we will determine how to calculate this force, and then examine an example of particular significance to magnetic levitation: repulsion between parallel wires. Calculating Magnetic ForceForce on a moving chargeFor a moving point charge, the magnetic force is proportional to both the magnetic field strength and the velocity of the charge. Furthermore, the direction of this force is perpendicular to both the velocity and the field (direction given by right-hand rule). Thus, the magnetic force is given by:Force on a current-carrying wire For a current in a wire, the magnetic force is proportional to the current, the length of the wire, and the magnetic field strength. Direction is perpendicular to current direction and magnetic field.Thus, the magnetic force equation looks very similar to that for a moving point charge:Parallel Wires Intro The repulsion or attraction between two parallel wires is of particular importance to magnetic levitation. The setup is as follows:If the currents flow in the same direction (as shown), the wires attract. If the currents flow in opposite directions, the wires repel.CalculationsTo calculate the force of repulsion, we first calculate the field produced by wire 1:Next, we use B1 to find the force on wire 2 due to wire 1:SummaryWe now know how to determine the force on a moving charge due to a magnetic field, and how to determine the force of attraction or repulsion betwe...
