IB Physics

AP Physics 

 Since an electric current is just a bunch of moving charges, wires carrying current will be subject to a force when in a magnetic field. When dealing with a current in a wire, we obviously can’t use units of q and v. However, qv can equally be expressed in terms of IL, where I is the current in a wire, and L is the length, in meters, of the wire—both qv and Il are expressed in units of C · m/s. So we can reformulate the equation for the magnitude of a magnetic force in order to apply it to a current-carrying wire:

 I L B Sin O = F

 In this formulation, O is the angle the wire makes with the magnetic field. We determine the direction of the force by using the right-hand rule between the direction of the current and that of the magnetic field.