Which law is commonly used when troubleshooting electrical systems?

• A. Kirchhoff's Laws
• B. Faraday's Law
• C. Lenz's Law
• D. Ohm's Law

Answer: (D)

When troubleshooting electrical systems, use Ohm's Law as the practical diagnostic tool because it directly links voltage, current, and resistance in a simple, testable relationship. If you know two of the quantities, you can calculate the third and see if the component or path is behaving as expected. For instance, measuring the supply voltage and the current through a circuit lets you compute the resistance the circuit presents; if that resistance doesn’t match the component’s rated value, you’ve likely found a fault such as a degraded connection, an opening, or a short. This approach is especially common in aircraft electrical systems with DC networks, where quick checks with a multimeter can reveal whether a wire, connector, or device is within spec. Other laws describe how currents and voltages behave in more complex networks or under changing magnetic fields, but they’re less directly useful for quick fault isolation. Ohm's Law gives you an immediate, actionable path to identify and diagnose issues.