Electromagnetism: Forces in a Magnetic Field

Force on a Current-carrying Conductor in a Magnetic FieldF = ILB This formula is only true if the flow of current is perpendicular to the magnetic field F = force I = current L = length B = magnetic flux density This force occurs because the conductor has a magnetic field around it When this magnetic field interacts with the magnetic field the conductor is placed in, the fields interact and create a force

The direction of the force can be found using Fleming's left-hand rule: Hold your thumb, first finger and second finger at right angles to one another If you place your first finger in the direction of the magnetic field, and your second finger in the direction of the current then your thumb shows the direction of the force

Force on a Charged Particle Moving through a Magnetic FieldF = qvB F = force q = charge v = velocity B = magnetic flux density

Forces between currents If two current-carrying conductors are placed in close proximity to one another, they will exert a force on each other due to their magnetic fields The unit of current, the ampere, is based on this principle The ampere is the steady current which, if maintained in two straight parallel conductors of infinite length, of negligible cross section and placed one metre apart in a vacuum would produce a force on each conductor of 2 × 10*-7 newtons per metre of length

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