Drawing of a potentiometer (variable resistor) with the case cut away, showing internal parts, from an advertisement in an electronics magazine. The labeled parts are :A. Shaft :B. Stationary carbon composition resistance element :C. Springy phosphor bronze wiper that rides along resistance element :D. Shaft attached to wiper :E, G Terminals connected to ends of resistance element :F. Terminal connected to wiper :H. Cam that operates on-off switch, if one is included in potentiometer Alterations to image: cloned out advertising copy, added arrows and labels