FAA Powerplant Written Practice Test

Which wire gauge number produces the least heat with a given voltage per length of conductor?

1. #10 gauge wire

2. #00 gauge wire

3. #14 gauge wire

4. #20 gauge wire

The correct answer is: #00 gauge wire

The wire gauge number is inversely related to the diameter of the wire; a lower gauge number corresponds to a thicker wire. Thicker wire, such as #00 gauge, has a lower electrical resistance compared to thinner wire, which means it can carry the same amount of current with less energy lost as heat. When a given voltage is applied across a length of conductor, the amount of heat generated can be understood using Joule's Law, which states that heat produced in a conductor is proportional to the square of the current flowing through it multiplied by the resistance of the conductor. Since thicker wires have lower resistance, they allow a greater current to flow with less heat production for the same voltage, making them more efficient. In contrast, thinner wires, such as #10, #14, or #20 gauge, have higher resistance. As a result, for the same amount of current, they would produce more heat due to the greater resistance. This understanding is crucial in selecting wire sizes for electrical applications to ensure safety and efficiency, especially in high-power scenarios where overheating can lead to failures or fire hazards.