The strength of a magnetic field is also known as the magnetic flux density and is given the symbol B. The magnetic field strength B is the force per unit current length on a wire carrying current I in the magnetic field when the current is at right angles to the magnetic field and is measured in tesla (T). If the field and current are not at right angles to each other, then the component of the field perpendicular to the current is equal to BsinΘ where Θ is the angle between the wire and the magnetic field. The force F on the wire can be measured using a current-balance where F = BIL.