CONDUCTIVITY PUTTY
A versatile aid for the teaching of resistivity and the dependence of resistance on the length and cross sectional area of a conductor. The cylinder of conductivity putty, 60mm long x 20mm dia. has a resistance of 20-Ohms. 100g pack.
In senior level the conductivity putty can be used to show how the capacitance of a sphere varies with the radius by using a digital coulomb meter.