Conducting putty is a unique and versatile aid to teaching the topic of resistivity and the dependence of resistance on length and cross-sectional area of the conductor.
The material is supplied in ‘blobs’ of approximately 100g in mass.
A conductive putty cylinder 60mm long and 20mm in diameter has a resistance of about 20Ω. Coins or washers placed on the ends of the cylinder can be used to connect it into a circuit. By altering the length and diameter in simple multiples, the relationship can quickly be established.
The substance is harmless, but messy, so plastic gloves are supplied for handling the putty.