Abstract: A slider arrangement for potentiometers is presented, which provides good contact between the potentiometer resistor and the slider with low friction and low wear. With each position of slider guide means, the slider contacts the potentiometer resistor in an associated well defined point regardless of the direction of movement of the guide means. To this end the slider comprises a wire helix in crossed relation to the potentiometer resistor. The wire helix is urged into engagement with the potentiometer resistor by a strap extending into the wire helix and engaging the inner side thereof under spring tension, whereby engagement between helix and strap and the required contact pressure between helix and potentiometer resistor is established. The strap has bays or recesses in the area of the potentiometer resistor to permit the turns of the wire helix to conform to the cross sectional contour of the resistor.

Abstract: A coating applied to a workpiece is removed therefrom and measured to determine the surface area of the workpiece.