R Wire Board. This apparatus provides the basis for student investigations into resistance. Four wires, 500mm long mounted on an acrylic base and connected via 4mm sockets. The wires are all Nichrome with diameters of 1.0, 0.8, 0.63 and 0.4mm giving resistances in the range 0.4 to ohms. graduated mm scale is included allowing resistance length and resistance diameter investigations to be easily covered. Dimensions (L): 500mm.