Bifilar Suspension

Bifilar Suspension, an arrangement adopted in many electrical and other instruments for the horizontal suspension of needles by means of two parallel fibres. A needle thus hung, with the fibres fixed to it symmetrically, is subject to a definite controlling force. For if by electro-magnetic or other action a deflecting force causes the needle to turn out of its position of rest, it will be slightly raised, an action which is opposed by the weight of the needle. The closer the two fibres the less will be the lift of the needle for a given deflection; hence the smaller the controlling force.