Dominate the AMPP Cathodic Protection Technician (CP2) Test 2026 – Unleash Your Tech Power!

To determine the resistance of the pipe section being tested using a 4 wire test, the concept of voltage and current in Ohm's Law is crucial.

Ohm's Law states that resistance (R) can be calculated using the formula R = V/I, where V is the voltage measured across the device and I is the current flowing through it. In this case, you have two voltage readings recorded when a test current of 10 A is applied: +21 mV and -19 mV.

First, you need to find the total voltage difference which will be the absolute difference between the two readings:

V_total = |(+21 mV)| + |(-19 mV)| = 21 mV + 19 mV = 40 mV.

Next, you will convert the voltage from millivolts to volts for ease of calculation:

40 mV = 0.040 V.

Now, applying Ohm's law:

R = V/I = 0.040 V / 10 A = 0.004 ohms, or in milliohms, that equals 4 m ohms.

Thus, the correct resistance of the pipe section being tested is 4 m ohms, aligning with the