Magnetic fields surround magnetic materials and electric currents and are detected by the force they exert on other magnetic materials and moving electric charges. The magnetic field at any given point is specified by both a direction and a magnitude (or strength); as such it is a vector field.In view of special relativity, the electric and magnetic fields are two interrelated aspects of a single object, called the electromagnetic field. A pure electric field in one reference frame is observed as a combination of both an electric field and a magnetic field in a moving reference frame.In modern physics, the magnetic (and electric) fields are understood to be due to a photon field; in the language of the Standard Model the electromagnetic force is mediated by photons
A magnetic field exerts a force on a conductor carrying a current.
If the wire is straight, and the field is uniform, the force is given by F = I L x B, where I is the current, L
is a vector whose magnitude is the length of the conductor and whose direction is the same as the direction of
the current, and B is the magnetic field vector.
If the shape of the wire is arbitrary, the force on a segment ds of
the wire is dF = I ds x B. The total force on the wire is obtained by integrating dF over the length of the
Magnetic Force on a Current Carrying Conductor
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