Magnetic Force 10 20 14 9 18 AM We know how to calculate B what is the force exerted on other charges and other currents due to the B Ampere s Experiments led to the following relationship Comparison Magnetic Work Point charge moving in a uniform magnetic field B o v changes during the motion but v magnitude of the velocity remains constant Synchrotrons and Particle Accelerators Accelerating direction of velocity changes not magnitude charges radiate light o Synchrotrons Special cases Hall Effect The particle is not free because it is in a solid Note in below the positve charges will accumulate on the right side of the solid not on the wire The separation of charges seen above will continue until the electric force exactly counters the magnetic force and then the charges will just go straight through the solid Measuring V Hall and current implies o that we can find magnetic field scalar for a given n number density of charges o or that we can find n number density of charges for a given magnetic field vector o If the moving charges are positive then the right side is o If the moving charges are negative then the right side is positive voltage negative voltage So far we found forces on moving charges what about forces on steady currents so we want to find the force as a function of current In general o o For a straight wire of finite length L Magnetic force balance o The magnetic force from the sides F1 and F2 cancel each other out o For a straight wire o If the loop is entirely immersed in the magnetic field then the top and bottom magnetic forces would cancel each other out and there would be no net magnetic force If the entire loop was immersed inside the magnetic field there would be no net magnetic force but there is a net torque Example of above Force between two current carrying wires o Generally first find the external magnetic field then the force More stuff Parallel Currents Anti Parallel Currents o o Perpendicular Currents o
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