4 Point Method / Measurement of low resistances / Ohm's Law

Principle

The resistances of various DC conductors are determined by recording the current / voltage characteristic. The resistivity of metal rods and the contact resistance of connecting cords are calculated.

Benefits

• Measurement at two different metals possible
• Conductivity rods can be used both for electrical and thermal conductivity experiments
• Measurement amplifier can be used for both AC and DC measurements and amplifies up to 10,000 times

Tasks

1. To plot the current / voltage characteristics of metal rods (copper and aluminium) and to calculate their resistivity.
2. To determine the resistance of various connecting cords by plotting their current / voltage characteristics and calculating the contact resistances.

Learning objectives

• Ohm's law
• Resistivity
• Contact resistance
• Conductivity
• Four-wire method of measurement