An engineering student is investigating how the electrical resistance of a 3D-printed conductive polymer filament varies with its length.
Describe how an ammeter and a voltmeter should be connected to the polymer filament to enable the student to determine its resistance.
Conductive polymers are highly sensitive to thermal variations. The student is advised to open the switch in the circuit between taking readings at different lengths. Explain how this practice improves the accuracy of the investigation.
To make electrical contacts at precise intervals along the filament, the student can use either a wide alligator clip or a fine, sharp-pointed needle probe. Explain why using the needle probe instead of the alligator clip improves: